From 484194dbf41758eec0ef62fef5fe9350c21b9241 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 6 May 2015 18:37:19 -0400 Subject: fix stack protector crashes on x32 & powerpc due to misplaced TLS canary i386, x86_64, x32, and powerpc all use TLS for stack protector canary values in the default stack protector ABI, but the location only matched the ABI on i386 and x86_64. on x32, the expected location for the canary contained the tid, thus producing spurious mismatches (resulting in process termination) upon fork. on powerpc, the expected location contained the stdio_locks list head, so returning from a function after calling flockfile produced spurious mismatches. in both cases, the random canary was not present, and a predictable value was used instead, making the stack protector hardening much less effective than it should be. in the current fix, the thread structure has been expanded to have canary fields at all three possible locations, and archs that use a non-default location must define a macro in pthread_arch.h to choose which location is used. for most archs (which lack TLS canary ABI) the choice does not matter. --- src/internal/pthread_impl.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'src/internal/pthread_impl.h') diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h index 56877b3a..e29f9c82 100644 --- a/src/internal/pthread_impl.h +++ b/src/internal/pthread_impl.h @@ -16,7 +16,7 @@ struct pthread { struct pthread *self; void **dtv, *unused1, *unused2; uintptr_t sysinfo; - uintptr_t canary; + uintptr_t canary, canary2; pid_t tid, pid; int tsd_used, errno_val; volatile int cancel, canceldisable, cancelasync; @@ -47,6 +47,7 @@ struct pthread { char *dlerror_buf; int dlerror_flag; void *stdio_locks; + uintptr_t canary_at_end; void **dtv_copy; }; @@ -89,6 +90,10 @@ struct __timer { #include "pthread_arch.h" +#ifndef CANARY +#define CANARY canary +#endif + #define SIGTIMER 32 #define SIGCANCEL 33 #define SIGSYNCCALL 34 -- cgit v1.2.1