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https://github.com/Divested-Mobile/DivestOS-Build.git
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76 lines
3.6 KiB
Diff
76 lines
3.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Renlord <me@renlord.com>
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Date: Thu, 12 Sep 2019 14:51:51 +1000
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Subject: [PATCH] add guard page(s) between static_tls and stack
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---
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libc/bionic/pthread_create.cpp | 29 +++++++++++++++++++----------
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1 file changed, 19 insertions(+), 10 deletions(-)
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diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
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index 4cf14ad72..6bbf970a0 100644
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--- a/libc/bionic/pthread_create.cpp
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+++ b/libc/bionic/pthread_create.cpp
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@@ -218,9 +218,10 @@ int __init_thread(pthread_internal_t* thread) {
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ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_size) {
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const StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
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- // Allocate in order: stack guard, stack, static TLS, guard page.
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+ // Allocate in order: stack guard, stack, guard page, static TLS, guard page.
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size_t mmap_size;
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if (__builtin_add_overflow(stack_size, stack_guard_size, &mmap_size)) return {};
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+ if (__builtin_add_overflow(mmap_size, PTHREAD_GUARD_SIZE, &mmap_size)) return {};
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if (__builtin_add_overflow(mmap_size, layout.size(), &mmap_size)) return {};
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if (__builtin_add_overflow(mmap_size, PTHREAD_GUARD_SIZE, &mmap_size)) return {};
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@@ -229,8 +230,8 @@ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_si
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mmap_size = __BIONIC_ALIGN(mmap_size, PAGE_SIZE);
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if (mmap_size < unaligned_size) return {};
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- // Create a new private anonymous map. Make the entire mapping PROT_NONE, then carve out a
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- // read+write area in the middle.
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+ // Create a new private anonymous map. Make the entire mapping PROT_NONE, then carve out
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+ // read+write areas for the stack and static TLS
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const int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE;
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char* const space = static_cast<char*>(mmap(nullptr, mmap_size, PROT_NONE, flags, -1, 0));
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if (space == MAP_FAILED) {
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@@ -240,13 +241,21 @@ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_si
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mmap_size, strerror(errno));
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return {};
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}
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- const size_t writable_size = mmap_size - stack_guard_size - PTHREAD_GUARD_SIZE;
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- if (mprotect(space + stack_guard_size,
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- writable_size,
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- PROT_READ | PROT_WRITE) != 0) {
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+
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+ if (mprotect(space + stack_guard_size, stack_size, PROT_READ | PROT_WRITE) != 0) {
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async_safe_format_log(ANDROID_LOG_WARN, "libc",
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"pthread_create failed: couldn't mprotect R+W %zu-byte thread mapping region: %s",
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- writable_size, strerror(errno));
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+ stack_size, strerror(errno));
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+ munmap(space, mmap_size);
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+ return {};
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+ }
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+
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+ char* const static_tls_space = space + stack_guard_size + stack_size + PTHREAD_GUARD_SIZE;
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+
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+ if (mprotect(static_tls_space, layout.size(), PROT_READ | PROT_WRITE) != 0) {
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+ async_safe_format_log(ANDROID_LOG_WARN, "libc",
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+ "pthread_create failed: couldn't mprotect R+W %zu-byte static TLS mapping region: %s",
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+ layout.size(), strerror(errno));
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munmap(space, mmap_size);
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return {};
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}
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@@ -254,9 +263,9 @@ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_si
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ThreadMapping result = {};
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result.mmap_base = space;
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result.mmap_size = mmap_size;
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- result.static_tls = space + mmap_size - PTHREAD_GUARD_SIZE - layout.size();
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+ result.static_tls = static_tls_space;
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result.stack_base = space;
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- result.stack_top = result.static_tls;
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+ result.stack_top = space + stack_guard_size + stack_size;
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return result;
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}
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