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https://github.com/Divested-Mobile/DivestOS-Build.git
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58 lines
3.0 KiB
Diff
58 lines
3.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Micay <danielmicay@gmail.com>
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Date: Thu, 10 Oct 2019 22:52:49 -0400
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Subject: [PATCH] move pthread_internal_t behind guard page
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---
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libc/bionic/pthread_create.cpp | 19 +++++++++----------
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1 file changed, 9 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 6bbf970a0..b4a044db1 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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@@ -218,10 +218,13 @@ 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, guard page, static TLS, guard page.
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+ size_t thread_page_size = __BIONIC_ALIGN(sizeof(pthread_internal_t), PAGE_SIZE);
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+
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+ // Allocate in order: stack guard, stack, guard page, pthread_internal_t, 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, thread_page_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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@@ -250,9 +253,10 @@ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_si
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return {};
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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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+ char* const thread = space + stack_guard_size + stack_size + PTHREAD_GUARD_SIZE;
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+ char* const static_tls_space = thread + thread_page_size;
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- if (mprotect(static_tls_space, layout.size(), PROT_READ | PROT_WRITE) != 0) {
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+ if (mprotect(thread, thread_page_size + 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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@@ -295,13 +299,8 @@ static int __allocate_thread(pthread_attr_t* attr, bionic_tcb** tcbp, void** chi
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stack_top = static_cast<char*>(attr->stack_base) + attr->stack_size;
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}
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- // Carve out space from the stack for the thread's pthread_internal_t. This
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- // memory isn't counted in pthread_attr_getstacksize.
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-
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- // To safely access the pthread_internal_t and thread stack, we need to find a 16-byte aligned boundary.
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- stack_top = align_down(stack_top - sizeof(pthread_internal_t), 16);
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-
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- pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top);
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+ pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(
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+ mapping.static_tls - __BIONIC_ALIGN(sizeof(pthread_internal_t), PAGE_SIZE));
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if (!stack_clean) {
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// If thread was not allocated by mmap(), it may not have been cleared to zero.
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// So assume the worst and zero it.
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