mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-12-24 15:09:34 -05:00
1705545d22
TODO: - manifest - devices - a few small patches to rebase Signed-off-by: Tad <tad@spotco.us>
42 lines
1.8 KiB
Diff
42 lines
1.8 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
From: Daniel Micay <danielmicay@gmail.com>
|
|
Date: Sun, 12 Mar 2017 17:49:13 -0400
|
|
Subject: [PATCH] on 64-bit, zero the leading stack canary byte
|
|
|
|
This reduces entropy of the canary from 64-bit to 56-bit in exchange for
|
|
mitigating non-terminated C string overflows.
|
|
|
|
Signed-off-by: anupritaisno1 <www.anuprita804@gmail.com>
|
|
---
|
|
libc/bionic/__libc_init_main_thread.cpp | 10 ++++++++++
|
|
1 file changed, 10 insertions(+)
|
|
|
|
diff --git a/libc/bionic/__libc_init_main_thread.cpp b/libc/bionic/__libc_init_main_thread.cpp
|
|
index 7e1e7cbcb..5bdf61d2c 100644
|
|
--- a/libc/bionic/__libc_init_main_thread.cpp
|
|
+++ b/libc/bionic/__libc_init_main_thread.cpp
|
|
@@ -49,6 +49,12 @@ uintptr_t __stack_chk_guard[PAGE_SIZE / sizeof(uintptr_t)] = {0};
|
|
|
|
static pthread_internal_t main_thread;
|
|
|
|
+#if __LP64__
|
|
+static const uintptr_t canary_mask = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ ?
|
|
+ 0xffffffffffffff00UL :
|
|
+ 0x00ffffffffffffffUL;
|
|
+#endif
|
|
+
|
|
// Setup for the main thread. For dynamic executables, this is called by the
|
|
// linker _before_ libc is mapped in memory. This means that all writes to
|
|
// globals from this function will apply to linker-private copies and will not
|
|
@@ -117,6 +123,10 @@ extern "C" void android_reset_stack_guards() {
|
|
// before we initialize the TLS. Dynamic executables will initialize their copy of the global
|
|
// stack protector from the one in the main thread's TLS.
|
|
__libc_safe_arc4random_buf(&__stack_chk_guard[0], sizeof(__stack_chk_guard[0]));
|
|
+#if __LP64__
|
|
+ // Sacrifice 8 bits of entropy on 64-bit to mitigate non-terminated C string overflows
|
|
+ __stack_chk_guard[0] &= canary_mask;
|
|
+#endif
|
|
if (mprotect(__stack_chk_guard, sizeof(__stack_chk_guard), PROT_READ) == -1) {
|
|
async_safe_fatal("mprotect __stack_chk_guard: %s", strerror(errno));
|
|
}
|