path: root/src/env/__stack_chk_fail.c
diff options
authorRich Felker <>2012-05-03 20:42:45 -0400
committerRich Felker <>2012-05-03 20:42:45 -0400
commit58aa5f45ed3282751ae118c107ff008d4df765dc (patch)
tree94859368fee26181f59f2b98911f1c46d146d25b /src/env/__stack_chk_fail.c
parente765239f334d670e1b68289a2fcaa6b82a3b9666 (diff)
overhaul SSP support to use a real canary
pthread structure has been adjusted to match the glibc/GCC abi for where the canary is stored on i386 and x86_64. it will need variants for other archs to provide the added security of the canary's entropy, but even without that it still works as well as the old "minimal" ssp support. eventually such changes will be made anyway, since they are also needed for GCC/C11 thread-local storage support (not yet implemented). care is taken not to attempt initializing the thread pointer unless the program actually uses SSP (by reference to __stack_chk_fail).
Diffstat (limited to 'src/env/__stack_chk_fail.c')
1 files changed, 13 insertions, 4 deletions
diff --git a/src/env/__stack_chk_fail.c b/src/env/__stack_chk_fail.c
index bbba3511..c6d0feb9 100644
--- a/src/env/__stack_chk_fail.c
+++ b/src/env/__stack_chk_fail.c
@@ -1,11 +1,20 @@
+#include <string.h>
+#include <inttypes.h>
+#include <elf.h>
#include "pthread_impl.h"
#include "atomic.h"
-void __init_ssp(void)
+uintptr_t __stack_chk_guard;
+void __init_ssp(size_t *auxv)
-#ifndef __PIC__
- __pthread_self_init();
+ size_t i;
+ pthread_t self = __pthread_self_init();
+ uintptr_t canary;
+ for (i=0; auxv[i] && auxv[i]!=AT_RANDOM; i+=2);
+ if (auxv[i]) memcpy(&canary, (void *)auxv[i+1], sizeof canary);
+ else canary = (uintptr_t)&canary * 1103515245;
+ __stack_chk_guard = self->canary = canary;
void __stack_chk_fail(void)