fix double-processing of DT_RELR relocations in ldso relocating itself

[musl] / src / env / __stack_chk_fail.c

diff --git a/src/env/__stack_chk_fail.c b/src/env/__stack_chk_fail.c
index daa1b07..e535260 100644 (file)
--- a/src/env/__stack_chk_fail.c
+++ b/src/env/__stack_chk_fail.c
@@ -1,21 +1,31 @@
 #include <string.h>
 #include <stdint.h>
 #include "pthread_impl.h"
-#include "atomic.h"
 
 uintptr_t __stack_chk_guard;
 
 void __init_ssp(void *entropy)
 {
-       pthread_t self = __pthread_self_init();
-       uintptr_t canary;
-       if (entropy) memcpy(&canary, entropy, sizeof canary);
-       else canary = (uintptr_t)&canary * 1103515245;
-       a_cas_l(&__stack_chk_guard, 0, canary);
-       self->canary = __stack_chk_guard;
+       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;
 }
 
 void __stack_chk_fail(void)
 {
        a_crash();
 }
+
+hidden void __stack_chk_fail_local(void);
+
+weak_alias(__stack_chk_fail, __stack_chk_fail_local);