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76 lines
3.1 KiB
Diff
76 lines
3.1 KiB
Diff
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From bb1107f7c6052c863692a41f78c000db792334bf Mon Sep 17 00:00:00 2001
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From: Michal Hocko <mhocko@suse.com>
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Date: Tue, 10 Jan 2017 16:57:27 -0800
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Subject: [PATCH] mm, slab: make sure that KMALLOC_MAX_SIZE will fit into
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MAX_ORDER
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Andrey Konovalov has reported the following warning triggered by the
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syzkaller fuzzer.
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WARNING: CPU: 1 PID: 9935 at mm/page_alloc.c:3511 __alloc_pages_nodemask+0x159c/0x1e20
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Kernel panic - not syncing: panic_on_warn set ...
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CPU: 1 PID: 9935 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #34
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Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
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Call Trace:
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__alloc_pages_slowpath mm/page_alloc.c:3511
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__alloc_pages_nodemask+0x159c/0x1e20 mm/page_alloc.c:3781
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alloc_pages_current+0x1c7/0x6b0 mm/mempolicy.c:2072
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alloc_pages include/linux/gfp.h:469
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kmalloc_order+0x1f/0x70 mm/slab_common.c:1015
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kmalloc_order_trace+0x1f/0x160 mm/slab_common.c:1026
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kmalloc_large include/linux/slab.h:422
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__kmalloc+0x210/0x2d0 mm/slub.c:3723
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kmalloc include/linux/slab.h:495
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ep_write_iter+0x167/0xb50 drivers/usb/gadget/legacy/inode.c:664
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new_sync_write fs/read_write.c:499
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__vfs_write+0x483/0x760 fs/read_write.c:512
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vfs_write+0x170/0x4e0 fs/read_write.c:560
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SYSC_write fs/read_write.c:607
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SyS_write+0xfb/0x230 fs/read_write.c:599
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entry_SYSCALL_64_fastpath+0x1f/0xc2
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The issue is caused by a lack of size check for the request size in
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ep_write_iter which should be fixed. It, however, points to another
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problem, that SLUB defines KMALLOC_MAX_SIZE too large because the its
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KMALLOC_SHIFT_MAX is (MAX_ORDER + PAGE_SHIFT) which means that the
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resulting page allocator request might be MAX_ORDER which is too large
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(see __alloc_pages_slowpath).
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The same applies to the SLOB allocator which allows even larger sizes.
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Make sure that they are capped properly and never request more than
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MAX_ORDER order.
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Link: http://lkml.kernel.org/r/20161220130659.16461-2-mhocko@kernel.org
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Signed-off-by: Michal Hocko <mhocko@suse.com>
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Reported-by: Andrey Konovalov <andreyknvl@google.com>
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Acked-by: Christoph Lameter <cl@linux.com>
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Cc: Alexei Starovoitov <ast@kernel.org>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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include/linux/slab.h | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/include/linux/slab.h b/include/linux/slab.h
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index 084b12bad1982..4c53635668154 100644
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--- a/include/linux/slab.h
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+++ b/include/linux/slab.h
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@@ -226,7 +226,7 @@ static inline const char *__check_heap_object(const void *ptr,
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* (PAGE_SIZE*2). Larger requests are passed to the page allocator.
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*/
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#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
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-#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
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+#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
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#ifndef KMALLOC_SHIFT_LOW
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#define KMALLOC_SHIFT_LOW 3
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#endif
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@@ -239,7 +239,7 @@ static inline const char *__check_heap_object(const void *ptr,
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* be allocated from the same page.
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*/
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#define KMALLOC_SHIFT_HIGH PAGE_SHIFT
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-#define KMALLOC_SHIFT_MAX 30
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+#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
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#ifndef KMALLOC_SHIFT_LOW
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#define KMALLOC_SHIFT_LOW 3
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#endif
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