DivestOS/Patches/LineageOS-21.0/android_bionic/0002-Graphene_Bionic_Hardening-15.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Fri, 11 Oct 2019 05:52:49 +0300
Subject: [PATCH] move pthread_internal_t behind guard page
---
libc/bionic/pthread_create.cpp | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index 88e57f973..f21e3a63f 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -212,10 +212,13 @@ int __init_thread(pthread_internal_t* thread) {
ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_size) {
const StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
- // Allocate in order: stack guard, stack, guard page, static TLS, guard page.
+ size_t thread_page_size = __BIONIC_ALIGN(sizeof(pthread_internal_t), PAGE_SIZE);
+
+ // Allocate in order: stack guard, stack, guard page, pthread_internal_t, static TLS, guard page.
size_t mmap_size;
if (__builtin_add_overflow(stack_size, stack_guard_size, &mmap_size)) return {};
if (__builtin_add_overflow(mmap_size, PTHREAD_GUARD_SIZE, &mmap_size)) return {};
+ if (__builtin_add_overflow(mmap_size, thread_page_size, &mmap_size)) return {};
if (__builtin_add_overflow(mmap_size, layout.size(), &mmap_size)) return {};
if (__builtin_add_overflow(mmap_size, PTHREAD_GUARD_SIZE, &mmap_size)) return {};
@@ -251,13 +254,14 @@ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_si
return {};
}
- char* const static_tls_space = space + stack_guard_size + stack_size + PTHREAD_GUARD_SIZE;
+ char* const thread = space + stack_guard_size + stack_size + PTHREAD_GUARD_SIZE;
+ char* const static_tls_space = thread + thread_page_size;
- if (mprotect(static_tls_space, layout.size(), PROT_READ | PROT_WRITE) != 0) {
+ if (mprotect(thread, thread_page_size + layout.size(), PROT_READ | PROT_WRITE) != 0) {
async_safe_format_log(
ANDROID_LOG_WARN, "libc",
- "pthread_create failed: couldn't mprotect R+W %zu-byte static TLS mapping region: %m",
- layout.size());
+ "pthread_create failed: couldn't mprotect R+W %zu-byte static TLS and pthread_internal mapping region: %m",
+ thread_page_size + layout.size());
munmap(space, mmap_size);
return {};
}
@@ -299,13 +303,8 @@ static int __allocate_thread(pthread_attr_t* attr, bionic_tcb** tcbp, void** chi
stack_top = static_cast<char*>(attr->stack_base) + attr->stack_size;
}
- // Carve out space from the stack for the thread's pthread_internal_t. This
- // memory isn't counted in pthread_attr_getstacksize.
-
- // To safely access the pthread_internal_t and thread stack, we need to find a 16-byte aligned boundary.
- stack_top = align_down(stack_top - sizeof(pthread_internal_t), 16);
-
- pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top);
+ pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(
+ mapping.static_tls - __BIONIC_ALIGN(sizeof(pthread_internal_t), PAGE_SIZE));
if (!stack_clean) {
// If thread was not allocated by mmap(), it may not have been cleared to zero.
// So assume the worst and zero it.