diff options
| -rw-r--r-- | src/env/__stack_chk_fail.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/env/__stack_chk_fail.c b/src/env/__stack_chk_fail.c index bf5a280a..e5352602 100644 --- a/src/env/__stack_chk_fail.c +++ b/src/env/__stack_chk_fail.c @@ -9,6 +9,15 @@ void __init_ssp(void *entropy) if (entropy) memcpy(&__stack_chk_guard, entropy, sizeof(uintptr_t)); else __stack_chk_guard = (uintptr_t)&__stack_chk_guard * 1103515245; +#if UINTPTR_MAX >= 0xffffffffffffffff + /* Sacrifice 8 bits of entropy on 64bit to prevent leaking/ + * overwriting the canary via string-manipulation functions. + * The NULL byte is on the second byte so that off-by-ones can + * still be detected. Endianness is taken care of + * automatically. */ + ((char *)&__stack_chk_guard)[1] = 0; +#endif + __pthread_self()->canary = __stack_chk_guard; } |