mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-10-01 01:35:54 -04:00
181519cf38
11b3a0c2c5db115412c37195#explicit zero 1131456ac632#brk 1158ebc243ea#random 115323b39f7e#undefined 116a91d9dddb#merge 11a042b5a0ba#vla formatting 119ec639de1b#pthread 1149571a0a49#read only 11149cc5ccb8#zero 112e613ccbe7#fork mmap 11e239c7dff8#memprot pthread 110b03d92b7f#xor 11de08419b82#junk 11897d4903e2#guard 11648cd68ca3#ptrhread guard 110bc4dbcbd2#stack rand 10aa9cc05d0710a8cdbb6352#explicit zero 10b28302c668#brk 109f8be7d07c#random 10cb91a7ee3a#undefined 1008279e2fdd#merge 106a18bd565d#vla formatting 102f392c2d08#pthread 108bbce1bc50#read only 10725f61db82#zero 104cd257135f#fork mmap 109220cf622b#memprot pthread 108ef71d1ffd#memprot exit 100eaef1abbd#xor 1064f1cc2148#junk 105c42a527cf#guard 105cc8c34e60#pthread guard 107f61cc8a1c#stack rand 9abdf523d269e4b9b31e6f#explicit zero 9a3a22a63d2#brk 97444dbc3cf#random 9dcd3b72ac9#undefined 9543e1df342#merge 9611e5691f7#vla formatting 98de97ce864#pthread 9a475717042#read only 97f0947cc0e#zero 9e9751d3370#fork mmap 983cd86d0d5#memprot pthread 91ebb165455#memprot exit 9488ba483cf#xor 9f9351d884b#junk 985e5bca0a5#move Signed-off-by: Tad <tad@spotco.us>
41 lines
1.8 KiB
Diff
41 lines
1.8 KiB
Diff
From 725f61db82eb41098291ce06445ccfbf5d5b3581 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.
|
|
---
|
|
libc/bionic/__libc_init_main_thread.cpp | 11 +++++++++--
|
|
1 file changed, 9 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/libc/bionic/__libc_init_main_thread.cpp b/libc/bionic/__libc_init_main_thread.cpp
|
|
index 2e3967daab..f5128de9ec 100644
|
|
--- a/libc/bionic/__libc_init_main_thread.cpp
|
|
+++ b/libc/bionic/__libc_init_main_thread.cpp
|
|
@@ -49,8 +49,11 @@ uintptr_t __stack_chk_guard[PAGE_SIZE / sizeof(uintptr_t)] = {0};
|
|
|
|
static pthread_internal_t main_thread;
|
|
|
|
-void __libc_init_global_stack_chk_guard(KernelArgumentBlock& args) {
|
|
-}
|
|
+#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
|
|
@@ -108,6 +111,10 @@ extern "C" void __libc_init_main_thread_late() {
|
|
// 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));
|
|
}
|