mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
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875 lines
30 KiB
Diff
875 lines
30 KiB
Diff
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From d4712eb79b17d85c9e354efa2d3156ce50736128 Mon Sep 17 00:00:00 2001
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From: Hugh Dickins <hughd@google.com>
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Date: Mon, 19 Jun 2017 04:03:24 -0700
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Subject: mm: larger stack guard gap, between vmas
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commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
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Stack guard page is a useful feature to reduce a risk of stack smashing
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into a different mapping. We have been using a single page gap which
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is sufficient to prevent having stack adjacent to a different mapping.
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But this seems to be insufficient in the light of the stack usage in
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userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
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used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
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which is 256kB or stack strings with MAX_ARG_STRLEN.
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This will become especially dangerous for suid binaries and the default
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no limit for the stack size limit because those applications can be
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tricked to consume a large portion of the stack and a single glibc call
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could jump over the guard page. These attacks are not theoretical,
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unfortunatelly.
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Make those attacks less probable by increasing the stack guard gap
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to 1MB (on systems with 4k pages; but make it depend on the page size
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because systems with larger base pages might cap stack allocations in
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the PAGE_SIZE units) which should cover larger alloca() and VLA stack
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allocations. It is obviously not a full fix because the problem is
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somehow inherent, but it should reduce attack space a lot.
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One could argue that the gap size should be configurable from userspace,
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but that can be done later when somebody finds that the new 1MB is wrong
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for some special case applications. For now, add a kernel command line
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option (stack_guard_gap) to specify the stack gap size (in page units).
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Implementation wise, first delete all the old code for stack guard page:
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because although we could get away with accounting one extra page in a
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stack vma, accounting a larger gap can break userspace - case in point,
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a program run with "ulimit -S -v 20000" failed when the 1MB gap was
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counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
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and strict non-overcommit mode.
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Instead of keeping gap inside the stack vma, maintain the stack guard
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gap as a gap between vmas: using vm_start_gap() in place of vm_start
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(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
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places which need to respect the gap - mainly arch_get_unmapped_area(),
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and and the vma tree's subtree_gap support for that.
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Original-patch-by: Oleg Nesterov <oleg@redhat.com>
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Original-patch-by: Michal Hocko <mhocko@suse.com>
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Signed-off-by: Hugh Dickins <hughd@google.com>
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Acked-by: Michal Hocko <mhocko@suse.com>
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Tested-by: Helge Deller <deller@gmx.de> # parisc
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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[wt: backport to 4.11: adjust context]
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[wt: backport to 4.9: adjust context ; kernel doc was not in admin-guide]
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[wt: backport to 4.4: adjust context ; drop ppc hugetlb_radix changes]
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[wt: backport to 3.18: adjust context ; no FOLL_POPULATE ;
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s390 uses generic arch_get_unmapped_area()]
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Signed-off-by: Willy Tarreau <w@1wt.eu>
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[gkh: minor build fixes for 3.18]
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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Documentation/kernel-parameters.txt | 7 ++
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arch/arc/mm/mmap.c | 2 +-
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arch/arm/mm/mmap.c | 4 +-
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arch/frv/mm/elf-fdpic.c | 2 +-
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arch/mips/mm/mmap.c | 2 +-
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arch/parisc/kernel/sys_parisc.c | 15 ++--
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arch/powerpc/mm/slice.c | 2 +-
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arch/sh/mm/mmap.c | 4 +-
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arch/sparc/kernel/sys_sparc_64.c | 4 +-
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arch/sparc/mm/hugetlbpage.c | 2 +-
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arch/tile/mm/hugetlbpage.c | 2 +-
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arch/x86/kernel/sys_x86_64.c | 4 +-
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arch/x86/mm/hugetlbpage.c | 2 +-
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arch/xtensa/kernel/syscall.c | 2 +-
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fs/hugetlbfs/inode.c | 2 +-
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fs/proc/task_mmu.c | 4 -
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include/linux/mm.h | 53 ++++++-------
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mm/gup.c | 5 --
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mm/memory.c | 38 ---------
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mm/mmap.c | 149 +++++++++++++++++++++---------------
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20 files changed, 147 insertions(+), 158 deletions(-)
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diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
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index b2bdea19..9abe552 100644
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--- a/Documentation/kernel-parameters.txt
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+++ b/Documentation/kernel-parameters.txt
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@@ -3324,6 +3324,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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spia_pedr=
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spia_peddr=
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+ stack_guard_gap= [MM]
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+ override the default stack gap protection. The value
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+ is in page units and it defines how many pages prior
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+ to (for stacks growing down) resp. after (for stacks
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+ growing up) the main stack are reserved for no other
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+ mapping. Default value is 256 pages.
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+
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stacktrace [FTRACE]
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Enabled the stack tracer on boot up.
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diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
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index 2e06d56..cf4ae69 100644
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--- a/arch/arc/mm/mmap.c
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+++ b/arch/arc/mm/mmap.c
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@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
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index 5e85ed3..8f9d1cf 100644
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--- a/arch/arm/mm/mmap.c
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+++ b/arch/arm/mm/mmap.c
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@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c
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index 836f1470..efa59f1 100644
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--- a/arch/frv/mm/elf-fdpic.c
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+++ b/arch/frv/mm/elf-fdpic.c
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@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
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addr = PAGE_ALIGN(addr);
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vma = find_vma(current->mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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goto success;
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}
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diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
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index f1baadd..9be924f 100644
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--- a/arch/mips/mm/mmap.c
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+++ b/arch/mips/mm/mmap.c
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@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
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index 5aba01a..4dda73c 100644
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--- a/arch/parisc/kernel/sys_parisc.c
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+++ b/arch/parisc/kernel/sys_parisc.c
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@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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unsigned long len, unsigned long pgoff, unsigned long flags)
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{
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struct mm_struct *mm = current->mm;
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- struct vm_area_struct *vma;
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+ struct vm_area_struct *vma, *prev;
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unsigned long task_size = TASK_SIZE;
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int do_color_align, last_mmap;
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struct vm_unmapped_area_info info;
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@@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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else
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addr = PAGE_ALIGN(addr);
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- vma = find_vma(mm, addr);
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+ vma = find_vma_prev(mm, addr, &prev);
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if (task_size - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)) &&
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+ (!prev || addr >= vm_end_gap(prev)))
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goto found_addr;
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}
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@@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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const unsigned long len, const unsigned long pgoff,
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const unsigned long flags)
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{
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- struct vm_area_struct *vma;
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+ struct vm_area_struct *vma, *prev;
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struct mm_struct *mm = current->mm;
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unsigned long addr = addr0;
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int do_color_align, last_mmap;
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@@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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addr = COLOR_ALIGN(addr, last_mmap, pgoff);
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else
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addr = PAGE_ALIGN(addr);
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- vma = find_vma(mm, addr);
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+
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+ vma = find_vma_prev(mm, addr, &prev);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)) &&
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+ (!prev || addr >= vm_end_gap(prev)))
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goto found_addr;
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}
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diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
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index ded0ea1..4c14626 100644
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--- a/arch/powerpc/mm/slice.c
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+++ b/arch/powerpc/mm/slice.c
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@@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
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if ((mm->task_size - len) < addr)
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return 0;
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vma = find_vma(mm, addr);
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- return (!vma || (addr + len) <= vma->vm_start);
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+ return (!vma || (addr + len) <= vm_start_gap(vma));
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}
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static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
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diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
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index 6777177..7df7d59 100644
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--- a/arch/sh/mm/mmap.c
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+++ b/arch/sh/mm/mmap.c
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@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
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index c690c8e..7f0f7c01 100644
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--- a/arch/sparc/kernel/sys_sparc_64.c
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+++ b/arch/sparc/kernel/sys_sparc_64.c
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@@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
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vma = find_vma(mm, addr);
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if (task_size - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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@@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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vma = find_vma(mm, addr);
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if (task_size - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
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index 4242eab..2b6fae6 100644
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--- a/arch/sparc/mm/hugetlbpage.c
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+++ b/arch/sparc/mm/hugetlbpage.c
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@@ -115,7 +115,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
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addr = ALIGN(addr, HPAGE_SIZE);
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vma = find_vma(mm, addr);
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if (task_size - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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if (mm->get_unmapped_area == arch_get_unmapped_area)
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diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
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index 8a00c7b..52deac2 100644
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--- a/arch/tile/mm/hugetlbpage.c
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+++ b/arch/tile/mm/hugetlbpage.c
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@@ -237,7 +237,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
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addr = ALIGN(addr, huge_page_size(h));
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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if (current->mm->get_unmapped_area == arch_get_unmapped_area)
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diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
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index 30277e2..d050393 100644
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--- a/arch/x86/kernel/sys_x86_64.c
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+++ b/arch/x86/kernel/sys_x86_64.c
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@@ -127,7 +127,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (end - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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@@ -166,7 +166,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
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index 9161f76..c504866 100644
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--- a/arch/x86/mm/hugetlbpage.c
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+++ b/arch/x86/mm/hugetlbpage.c
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@@ -144,7 +144,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
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addr = ALIGN(addr, huge_page_size(h));
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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- (!vma || addr + len <= vma->vm_start))
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+ (!vma || addr + len <= vm_start_gap(vma)))
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return addr;
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}
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if (mm->get_unmapped_area == arch_get_unmapped_area)
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diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
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index 5d3f7a1..1ff0b92 100644
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--- a/arch/xtensa/kernel/syscall.c
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+++ b/arch/xtensa/kernel/syscall.c
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@@ -86,7 +86,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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/* At this point: (!vmm || addr < vmm->vm_end). */
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||
|
if (TASK_SIZE - len < addr)
|
||
|
return -ENOMEM;
|
||
|
- if (!vmm || addr + len <= vmm->vm_start)
|
||
|
+ if (!vmm || addr + len <= vm_start_gap(vmm))
|
||
|
return addr;
|
||
|
addr = vmm->vm_end;
|
||
|
if (flags & MAP_SHARED)
|
||
|
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
|
||
|
index 1e2872b..148c4e9 100644
|
||
|
--- a/fs/hugetlbfs/inode.c
|
||
|
+++ b/fs/hugetlbfs/inode.c
|
||
|
@@ -171,7 +171,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
|
||
|
addr = ALIGN(addr, huge_page_size(h));
|
||
|
vma = find_vma(mm, addr);
|
||
|
if (TASK_SIZE - len >= addr &&
|
||
|
- (!vma || addr + len <= vma->vm_start))
|
||
|
+ (!vma || addr + len <= vm_start_gap(vma)))
|
||
|
return addr;
|
||
|
}
|
||
|
|
||
|
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
|
||
|
index af33fb7..aea2d0b 100644
|
||
|
--- a/fs/proc/task_mmu.c
|
||
|
+++ b/fs/proc/task_mmu.c
|
||
|
@@ -284,11 +284,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
|
||
|
|
||
|
/* We don't show the stack guard page in /proc/maps */
|
||
|
start = vma->vm_start;
|
||
|
- if (stack_guard_page_start(vma, start))
|
||
|
- start += PAGE_SIZE;
|
||
|
end = vma->vm_end;
|
||
|
- if (stack_guard_page_end(vma, end))
|
||
|
- end -= PAGE_SIZE;
|
||
|
|
||
|
seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
|
||
|
seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
|
||
|
diff --git a/include/linux/mm.h b/include/linux/mm.h
|
||
|
index db853de..54ad2e4 100644
|
||
|
--- a/include/linux/mm.h
|
||
|
+++ b/include/linux/mm.h
|
||
|
@@ -1242,34 +1242,6 @@ int set_page_dirty_lock(struct page *page);
|
||
|
int clear_page_dirty_for_io(struct page *page);
|
||
|
int get_cmdline(struct task_struct *task, char *buffer, int buflen);
|
||
|
|
||
|
-/* Is the vma a continuation of the stack vma above it? */
|
||
|
-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
|
||
|
-{
|
||
|
- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
|
||
|
-}
|
||
|
-
|
||
|
-static inline int stack_guard_page_start(struct vm_area_struct *vma,
|
||
|
- unsigned long addr)
|
||
|
-{
|
||
|
- return (vma->vm_flags & VM_GROWSDOWN) &&
|
||
|
- (vma->vm_start == addr) &&
|
||
|
- !vma_growsdown(vma->vm_prev, addr);
|
||
|
-}
|
||
|
-
|
||
|
-/* Is the vma a continuation of the stack vma below it? */
|
||
|
-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
|
||
|
-{
|
||
|
- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
|
||
|
-}
|
||
|
-
|
||
|
-static inline int stack_guard_page_end(struct vm_area_struct *vma,
|
||
|
- unsigned long addr)
|
||
|
-{
|
||
|
- return (vma->vm_flags & VM_GROWSUP) &&
|
||
|
- (vma->vm_end == addr) &&
|
||
|
- !vma_growsup(vma->vm_next, addr);
|
||
|
-}
|
||
|
-
|
||
|
extern struct task_struct *task_of_stack(struct task_struct *task,
|
||
|
struct vm_area_struct *vma, bool in_group);
|
||
|
|
||
|
@@ -1930,6 +1902,7 @@ void page_cache_async_readahead(struct address_space *mapping,
|
||
|
|
||
|
unsigned long max_sane_readahead(unsigned long nr);
|
||
|
|
||
|
+extern unsigned long stack_guard_gap;
|
||
|
/* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
|
||
|
extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
|
||
|
|
||
|
@@ -1958,6 +1931,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
|
||
|
return vma;
|
||
|
}
|
||
|
|
||
|
+static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
|
||
|
+{
|
||
|
+ unsigned long vm_start = vma->vm_start;
|
||
|
+
|
||
|
+ if (vma->vm_flags & VM_GROWSDOWN) {
|
||
|
+ vm_start -= stack_guard_gap;
|
||
|
+ if (vm_start > vma->vm_start)
|
||
|
+ vm_start = 0;
|
||
|
+ }
|
||
|
+ return vm_start;
|
||
|
+}
|
||
|
+
|
||
|
+static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
|
||
|
+{
|
||
|
+ unsigned long vm_end = vma->vm_end;
|
||
|
+
|
||
|
+ if (vma->vm_flags & VM_GROWSUP) {
|
||
|
+ vm_end += stack_guard_gap;
|
||
|
+ if (vm_end < vma->vm_end)
|
||
|
+ vm_end = -PAGE_SIZE;
|
||
|
+ }
|
||
|
+ return vm_end;
|
||
|
+}
|
||
|
+
|
||
|
static inline unsigned long vma_pages(struct vm_area_struct *vma)
|
||
|
{
|
||
|
return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
|
||
|
diff --git a/mm/gup.c b/mm/gup.c
|
||
|
index 3cec4df..ce1630b 100644
|
||
|
--- a/mm/gup.c
|
||
|
+++ b/mm/gup.c
|
||
|
@@ -275,11 +275,6 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
|
||
|
unsigned int fault_flags = 0;
|
||
|
int ret;
|
||
|
|
||
|
- /* For mlock, just skip the stack guard page. */
|
||
|
- if ((*flags & FOLL_MLOCK) &&
|
||
|
- (stack_guard_page_start(vma, address) ||
|
||
|
- stack_guard_page_end(vma, address + PAGE_SIZE)))
|
||
|
- return -ENOENT;
|
||
|
if (*flags & FOLL_WRITE)
|
||
|
fault_flags |= FAULT_FLAG_WRITE;
|
||
|
if (nonblocking)
|
||
|
diff --git a/mm/memory.c b/mm/memory.c
|
||
|
index 6ca26c3..0c4f5e3 100644
|
||
|
--- a/mm/memory.c
|
||
|
+++ b/mm/memory.c
|
||
|
@@ -2580,40 +2580,6 @@ out_release:
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
- * This is like a special single-page "expand_{down|up}wards()",
|
||
|
- * except we must first make sure that 'address{-|+}PAGE_SIZE'
|
||
|
- * doesn't hit another vma.
|
||
|
- */
|
||
|
-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
|
||
|
-{
|
||
|
- address &= PAGE_MASK;
|
||
|
- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
|
||
|
- struct vm_area_struct *prev = vma->vm_prev;
|
||
|
-
|
||
|
- /*
|
||
|
- * Is there a mapping abutting this one below?
|
||
|
- *
|
||
|
- * That's only ok if it's the same stack mapping
|
||
|
- * that has gotten split..
|
||
|
- */
|
||
|
- if (prev && prev->vm_end == address)
|
||
|
- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
|
||
|
-
|
||
|
- return expand_downwards(vma, address - PAGE_SIZE);
|
||
|
- }
|
||
|
- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
|
||
|
- struct vm_area_struct *next = vma->vm_next;
|
||
|
-
|
||
|
- /* As VM_GROWSDOWN but s/below/above/ */
|
||
|
- if (next && next->vm_start == address + PAGE_SIZE)
|
||
|
- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
|
||
|
-
|
||
|
- return expand_upwards(vma, address + PAGE_SIZE);
|
||
|
- }
|
||
|
- return 0;
|
||
|
-}
|
||
|
-
|
||
|
-/*
|
||
|
* We enter with non-exclusive mmap_sem (to exclude vma changes,
|
||
|
* but allow concurrent faults), and pte mapped but not yet locked.
|
||
|
* We return with mmap_sem still held, but pte unmapped and unlocked.
|
||
|
@@ -2633,10 +2599,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
||
|
if (vma->vm_flags & VM_SHARED)
|
||
|
return VM_FAULT_SIGBUS;
|
||
|
|
||
|
- /* Check if we need to add a guard page to the stack */
|
||
|
- if (check_stack_guard_page(vma, address) < 0)
|
||
|
- return VM_FAULT_SIGSEGV;
|
||
|
-
|
||
|
/* Use the zero-page for reads */
|
||
|
if (!(flags & FAULT_FLAG_WRITE)) {
|
||
|
entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
|
||
|
diff --git a/mm/mmap.c b/mm/mmap.c
|
||
|
index f032671..14ccc94 100644
|
||
|
--- a/mm/mmap.c
|
||
|
+++ b/mm/mmap.c
|
||
|
@@ -290,6 +290,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
|
||
|
unsigned long retval;
|
||
|
unsigned long newbrk, oldbrk;
|
||
|
struct mm_struct *mm = current->mm;
|
||
|
+ struct vm_area_struct *next;
|
||
|
unsigned long min_brk;
|
||
|
bool populate;
|
||
|
|
||
|
@@ -334,7 +335,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
|
||
|
}
|
||
|
|
||
|
/* Check against existing mmap mappings. */
|
||
|
- if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
|
||
|
+ next = find_vma(mm, oldbrk);
|
||
|
+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
|
||
|
goto out;
|
||
|
|
||
|
/* Ok, looks good - let it rip. */
|
||
|
@@ -357,10 +359,22 @@ out:
|
||
|
|
||
|
static long vma_compute_subtree_gap(struct vm_area_struct *vma)
|
||
|
{
|
||
|
- unsigned long max, subtree_gap;
|
||
|
- max = vma->vm_start;
|
||
|
- if (vma->vm_prev)
|
||
|
- max -= vma->vm_prev->vm_end;
|
||
|
+ unsigned long max, prev_end, subtree_gap;
|
||
|
+
|
||
|
+ /*
|
||
|
+ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
|
||
|
+ * allow two stack_guard_gaps between them here, and when choosing
|
||
|
+ * an unmapped area; whereas when expanding we only require one.
|
||
|
+ * That's a little inconsistent, but keeps the code here simpler.
|
||
|
+ */
|
||
|
+ max = vm_start_gap(vma);
|
||
|
+ if (vma->vm_prev) {
|
||
|
+ prev_end = vm_end_gap(vma->vm_prev);
|
||
|
+ if (max > prev_end)
|
||
|
+ max -= prev_end;
|
||
|
+ else
|
||
|
+ max = 0;
|
||
|
+ }
|
||
|
if (vma->vm_rb.rb_left) {
|
||
|
subtree_gap = rb_entry(vma->vm_rb.rb_left,
|
||
|
struct vm_area_struct, vm_rb)->rb_subtree_gap;
|
||
|
@@ -453,7 +467,7 @@ static void validate_mm(struct mm_struct *mm)
|
||
|
anon_vma_unlock_read(anon_vma);
|
||
|
}
|
||
|
|
||
|
- highest_address = vma->vm_end;
|
||
|
+ highest_address = vm_end_gap(vma);
|
||
|
vma = vma->vm_next;
|
||
|
i++;
|
||
|
}
|
||
|
@@ -622,7 +636,7 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
|
||
|
if (vma->vm_next)
|
||
|
vma_gap_update(vma->vm_next);
|
||
|
else
|
||
|
- mm->highest_vm_end = vma->vm_end;
|
||
|
+ mm->highest_vm_end = vm_end_gap(vma);
|
||
|
|
||
|
/*
|
||
|
* vma->vm_prev wasn't known when we followed the rbtree to find the
|
||
|
@@ -874,7 +888,7 @@ again: remove_next = 1 + (end > next->vm_end);
|
||
|
vma_gap_update(vma);
|
||
|
if (end_changed) {
|
||
|
if (!next)
|
||
|
- mm->highest_vm_end = end;
|
||
|
+ mm->highest_vm_end = vm_end_gap(vma);
|
||
|
else if (!adjust_next)
|
||
|
vma_gap_update(next);
|
||
|
}
|
||
|
@@ -917,7 +931,7 @@ again: remove_next = 1 + (end > next->vm_end);
|
||
|
else if (next)
|
||
|
vma_gap_update(next);
|
||
|
else
|
||
|
- mm->highest_vm_end = end;
|
||
|
+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
|
||
|
}
|
||
|
if (insert && file)
|
||
|
uprobe_mmap(insert);
|
||
|
@@ -1740,7 +1754,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
||
|
|
||
|
while (true) {
|
||
|
/* Visit left subtree if it looks promising */
|
||
|
- gap_end = vma->vm_start;
|
||
|
+ gap_end = vm_start_gap(vma);
|
||
|
if (gap_end >= low_limit && vma->vm_rb.rb_left) {
|
||
|
struct vm_area_struct *left =
|
||
|
rb_entry(vma->vm_rb.rb_left,
|
||
|
@@ -1751,7 +1765,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
|
||
|
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
||
|
check_current:
|
||
|
/* Check if current node has a suitable gap */
|
||
|
if (gap_start > high_limit)
|
||
|
@@ -1778,8 +1792,8 @@ check_current:
|
||
|
vma = rb_entry(rb_parent(prev),
|
||
|
struct vm_area_struct, vm_rb);
|
||
|
if (prev == vma->vm_rb.rb_left) {
|
||
|
- gap_start = vma->vm_prev->vm_end;
|
||
|
- gap_end = vma->vm_start;
|
||
|
+ gap_start = vm_end_gap(vma->vm_prev);
|
||
|
+ gap_end = vm_start_gap(vma);
|
||
|
goto check_current;
|
||
|
}
|
||
|
}
|
||
|
@@ -1843,7 +1857,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
||
|
|
||
|
while (true) {
|
||
|
/* Visit right subtree if it looks promising */
|
||
|
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
|
||
|
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
||
|
if (gap_start <= high_limit && vma->vm_rb.rb_right) {
|
||
|
struct vm_area_struct *right =
|
||
|
rb_entry(vma->vm_rb.rb_right,
|
||
|
@@ -1856,7 +1870,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
||
|
|
||
|
check_current:
|
||
|
/* Check if current node has a suitable gap */
|
||
|
- gap_end = vma->vm_start;
|
||
|
+ gap_end = vm_start_gap(vma);
|
||
|
if (gap_end < low_limit)
|
||
|
return -ENOMEM;
|
||
|
if (gap_start <= high_limit && gap_end - gap_start >= length)
|
||
|
@@ -1882,7 +1896,7 @@ check_current:
|
||
|
struct vm_area_struct, vm_rb);
|
||
|
if (prev == vma->vm_rb.rb_right) {
|
||
|
gap_start = vma->vm_prev ?
|
||
|
- vma->vm_prev->vm_end : 0;
|
||
|
+ vm_end_gap(vma->vm_prev) : 0;
|
||
|
goto check_current;
|
||
|
}
|
||
|
}
|
||
|
@@ -1920,7 +1934,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
||
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
||
|
{
|
||
|
struct mm_struct *mm = current->mm;
|
||
|
- struct vm_area_struct *vma;
|
||
|
+ struct vm_area_struct *vma, *prev;
|
||
|
struct vm_unmapped_area_info info;
|
||
|
|
||
|
if (len > TASK_SIZE - mmap_min_addr)
|
||
|
@@ -1931,9 +1945,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
||
|
|
||
|
if (addr) {
|
||
|
addr = PAGE_ALIGN(addr);
|
||
|
- vma = find_vma(mm, addr);
|
||
|
+ vma = find_vma_prev(mm, addr, &prev);
|
||
|
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
|
||
|
- (!vma || addr + len <= vma->vm_start))
|
||
|
+ (!vma || addr + len <= vm_start_gap(vma)) &&
|
||
|
+ (!prev || addr >= vm_end_gap(prev)))
|
||
|
return addr;
|
||
|
}
|
||
|
|
||
|
@@ -1956,7 +1971,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
|
||
|
const unsigned long len, const unsigned long pgoff,
|
||
|
const unsigned long flags)
|
||
|
{
|
||
|
- struct vm_area_struct *vma;
|
||
|
+ struct vm_area_struct *vma, *prev;
|
||
|
struct mm_struct *mm = current->mm;
|
||
|
unsigned long addr = addr0;
|
||
|
struct vm_unmapped_area_info info;
|
||
|
@@ -1971,9 +1986,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
|
||
|
/* requesting a specific address */
|
||
|
if (addr) {
|
||
|
addr = PAGE_ALIGN(addr);
|
||
|
- vma = find_vma(mm, addr);
|
||
|
+ vma = find_vma_prev(mm, addr, &prev);
|
||
|
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
|
||
|
- (!vma || addr + len <= vma->vm_start))
|
||
|
+ (!vma || addr + len <= vm_start_gap(vma)) &&
|
||
|
+ (!prev || addr >= vm_end_gap(prev)))
|
||
|
return addr;
|
||
|
}
|
||
|
|
||
|
@@ -2099,21 +2115,19 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
|
||
|
* update accounting. This is shared with both the
|
||
|
* grow-up and grow-down cases.
|
||
|
*/
|
||
|
-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
|
||
|
+static int acct_stack_growth(struct vm_area_struct *vma,
|
||
|
+ unsigned long size, unsigned long grow)
|
||
|
{
|
||
|
struct mm_struct *mm = vma->vm_mm;
|
||
|
struct rlimit *rlim = current->signal->rlim;
|
||
|
- unsigned long new_start, actual_size;
|
||
|
+ unsigned long new_start;
|
||
|
|
||
|
/* address space limit tests */
|
||
|
if (!may_expand_vm(mm, grow))
|
||
|
return -ENOMEM;
|
||
|
|
||
|
/* Stack limit test */
|
||
|
- actual_size = size;
|
||
|
- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
|
||
|
- actual_size -= PAGE_SIZE;
|
||
|
- if (actual_size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
|
||
|
+ if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
|
||
|
return -ENOMEM;
|
||
|
|
||
|
/* mlock limit tests */
|
||
|
@@ -2154,17 +2168,30 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
|
||
|
*/
|
||
|
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
||
|
{
|
||
|
+ struct vm_area_struct *next;
|
||
|
+ unsigned long gap_addr;
|
||
|
int error = 0;
|
||
|
|
||
|
if (!(vma->vm_flags & VM_GROWSUP))
|
||
|
return -EFAULT;
|
||
|
|
||
|
/* Guard against wrapping around to address 0. */
|
||
|
- if (address < PAGE_ALIGN(address+4))
|
||
|
- address = PAGE_ALIGN(address+4);
|
||
|
- else
|
||
|
+ address &= PAGE_MASK;
|
||
|
+ address += PAGE_SIZE;
|
||
|
+ if (!address)
|
||
|
return -ENOMEM;
|
||
|
|
||
|
+ /* Enforce stack_guard_gap */
|
||
|
+ gap_addr = address + stack_guard_gap;
|
||
|
+ if (gap_addr < address)
|
||
|
+ return -ENOMEM;
|
||
|
+ next = vma->vm_next;
|
||
|
+ if (next && next->vm_start < gap_addr) {
|
||
|
+ if (!(next->vm_flags & VM_GROWSUP))
|
||
|
+ return -ENOMEM;
|
||
|
+ /* Check that both stack segments have the same anon_vma? */
|
||
|
+ }
|
||
|
+
|
||
|
/* We must make sure the anon_vma is allocated. */
|
||
|
if (unlikely(anon_vma_prepare(vma)))
|
||
|
return -ENOMEM;
|
||
|
@@ -2205,7 +2232,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
||
|
if (vma->vm_next)
|
||
|
vma_gap_update(vma->vm_next);
|
||
|
else
|
||
|
- vma->vm_mm->highest_vm_end = address;
|
||
|
+ vma->vm_mm->highest_vm_end = vm_end_gap(vma);
|
||
|
spin_unlock(&vma->vm_mm->page_table_lock);
|
||
|
|
||
|
perf_event_mmap(vma);
|
||
|
@@ -2225,6 +2252,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
||
|
int expand_downwards(struct vm_area_struct *vma,
|
||
|
unsigned long address)
|
||
|
{
|
||
|
+ struct vm_area_struct *prev;
|
||
|
+ unsigned long gap_addr;
|
||
|
int error;
|
||
|
|
||
|
address &= PAGE_MASK;
|
||
|
@@ -2232,6 +2261,17 @@ int expand_downwards(struct vm_area_struct *vma,
|
||
|
if (error)
|
||
|
return error;
|
||
|
|
||
|
+ /* Enforce stack_guard_gap */
|
||
|
+ gap_addr = address - stack_guard_gap;
|
||
|
+ if (gap_addr > address)
|
||
|
+ return -ENOMEM;
|
||
|
+ prev = vma->vm_prev;
|
||
|
+ if (prev && prev->vm_end > gap_addr) {
|
||
|
+ if (!(prev->vm_flags & VM_GROWSDOWN))
|
||
|
+ return -ENOMEM;
|
||
|
+ /* Check that both stack segments have the same anon_vma? */
|
||
|
+ }
|
||
|
+
|
||
|
/* We must make sure the anon_vma is allocated. */
|
||
|
if (unlikely(anon_vma_prepare(vma)))
|
||
|
return -ENOMEM;
|
||
|
@@ -2283,28 +2323,25 @@ int expand_downwards(struct vm_area_struct *vma,
|
||
|
return error;
|
||
|
}
|
||
|
|
||
|
-/*
|
||
|
- * Note how expand_stack() refuses to expand the stack all the way to
|
||
|
- * abut the next virtual mapping, *unless* that mapping itself is also
|
||
|
- * a stack mapping. We want to leave room for a guard page, after all
|
||
|
- * (the guard page itself is not added here, that is done by the
|
||
|
- * actual page faulting logic)
|
||
|
- *
|
||
|
- * This matches the behavior of the guard page logic (see mm/memory.c:
|
||
|
- * check_stack_guard_page()), which only allows the guard page to be
|
||
|
- * removed under these circumstances.
|
||
|
- */
|
||
|
+/* enforced gap between the expanding stack and other mappings. */
|
||
|
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
|
||
|
+
|
||
|
+static int __init cmdline_parse_stack_guard_gap(char *p)
|
||
|
+{
|
||
|
+ unsigned long val;
|
||
|
+ char *endptr;
|
||
|
+
|
||
|
+ val = simple_strtoul(p, &endptr, 10);
|
||
|
+ if (!*endptr)
|
||
|
+ stack_guard_gap = val << PAGE_SHIFT;
|
||
|
+
|
||
|
+ return 0;
|
||
|
+}
|
||
|
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
|
||
|
+
|
||
|
#ifdef CONFIG_STACK_GROWSUP
|
||
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
||
|
{
|
||
|
- struct vm_area_struct *next;
|
||
|
-
|
||
|
- address &= PAGE_MASK;
|
||
|
- next = vma->vm_next;
|
||
|
- if (next && next->vm_start == address + PAGE_SIZE) {
|
||
|
- if (!(next->vm_flags & VM_GROWSUP))
|
||
|
- return -ENOMEM;
|
||
|
- }
|
||
|
return expand_upwards(vma, address);
|
||
|
}
|
||
|
|
||
|
@@ -2326,14 +2363,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
||
|
#else
|
||
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
||
|
{
|
||
|
- struct vm_area_struct *prev;
|
||
|
-
|
||
|
- address &= PAGE_MASK;
|
||
|
- prev = vma->vm_prev;
|
||
|
- if (prev && prev->vm_end == address) {
|
||
|
- if (!(prev->vm_flags & VM_GROWSDOWN))
|
||
|
- return -ENOMEM;
|
||
|
- }
|
||
|
return expand_downwards(vma, address);
|
||
|
}
|
||
|
|
||
|
@@ -2429,7 +2458,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
|
||
|
vma->vm_prev = prev;
|
||
|
vma_gap_update(vma);
|
||
|
} else
|
||
|
- mm->highest_vm_end = prev ? prev->vm_end : 0;
|
||
|
+ mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
|
||
|
tail_vma->vm_next = NULL;
|
||
|
|
||
|
/* Kill the cache */
|
||
|
--
|
||
|
cgit v1.1
|
||
|
|