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Code Issues Projects Releases Wiki Activity

properly access mcontext_t program counter in cancellation handler

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using the actual mcontext_t definition rather than an overlaid pointer
array both improves correctness/readability and eliminates some ugly
hacks for archs with 64-bit registers bit 32-bit program counter.

also fix UB due to comparison of pointers not in a common array
object.
This commit is contained in:
Rich Felker
2015-11-02 12:39:28 -05:00
parent fead7e3fc0
commit cb1bf2f321
11 changed files with 14 additions and 15 deletions
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7
src/thread/pthread_cancel.c
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@ -1,3 +1,4 @@
#define _GNU_SOURCE
#include <string.h>
#include "pthread_impl.h"
#include "syscall.h"
@ -61,15 +62,15 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx)
{
pthread_t self = __pthread_self();
ucontext_t *uc = ctx;
const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
uintptr_t pc = uc->uc_mcontext.MC_PC;
a_barrier();
if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
_sigaddset(&uc->uc_sigmask, SIGCANCEL);
if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
((char **)&uc->uc_mcontext)[CANCEL_REG_IP] = (char *)__cp_cancel;
if (self->cancelasync || pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) {
uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel;
return;
}