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authorRoland McGrath <roland@redhat.com>2005-06-23 03:08:21 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 12:45:09 -0400
commit7c1def1652c6c1a95eafca2991baace34afaed0f (patch)
tree0175c6babb39233a5cbbdf3c8ca9027180f580ed /arch/i386
parent1946089a109251655c5438d92c539bd2930e71ea (diff)
[PATCH] i386: never block forced SIGSEGV
This problem was first noticed on PPC and has already been fixed there. But the exact same issue applies to other platforms in the same way. The signal blocking for sa_mask and the handled signal takes place after the handler setup. When the stack is bogus, the handler setup forces a SIGSEGV. But then this will be blocked, and returning to user mode will fault again and iterate. This patch fixes the problem by checking whether signal handler setup failed, and not doing the signal-blocking if so. This copies what was done in the ppc code. I think all architectures' signal handler setup code follows this pattern and needs the change. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/signal.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index ea46d028af08..344400787c39 100644
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -346,8 +346,8 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
346extern void __user __kernel_sigreturn; 346extern void __user __kernel_sigreturn;
347extern void __user __kernel_rt_sigreturn; 347extern void __user __kernel_rt_sigreturn;
348 348
349static void setup_frame(int sig, struct k_sigaction *ka, 349static int setup_frame(int sig, struct k_sigaction *ka,
350 sigset_t *set, struct pt_regs * regs) 350 sigset_t *set, struct pt_regs * regs)
351{ 351{
352 void __user *restorer; 352 void __user *restorer;
353 struct sigframe __user *frame; 353 struct sigframe __user *frame;
@@ -429,13 +429,14 @@ static void setup_frame(int sig, struct k_sigaction *ka,
429 current->comm, current->pid, frame, regs->eip, frame->pretcode); 429 current->comm, current->pid, frame, regs->eip, frame->pretcode);
430#endif 430#endif
431 431
432 return; 432 return 1;
433 433
434give_sigsegv: 434give_sigsegv:
435 force_sigsegv(sig, current); 435 force_sigsegv(sig, current);
436 return 0;
436} 437}
437 438
438static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 439static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
439 sigset_t *set, struct pt_regs * regs) 440 sigset_t *set, struct pt_regs * regs)
440{ 441{
441 void __user *restorer; 442 void __user *restorer;
@@ -522,20 +523,23 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
522 current->comm, current->pid, frame, regs->eip, frame->pretcode); 523 current->comm, current->pid, frame, regs->eip, frame->pretcode);
523#endif 524#endif
524 525
525 return; 526 return 1;
526 527
527give_sigsegv: 528give_sigsegv:
528 force_sigsegv(sig, current); 529 force_sigsegv(sig, current);
530 return 0;
529} 531}
530 532
531/* 533/*
532 * OK, we're invoking a handler 534 * OK, we're invoking a handler
533 */ 535 */
534 536
535static void 537static int
536handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 538handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
537 sigset_t *oldset, struct pt_regs * regs) 539 sigset_t *oldset, struct pt_regs * regs)
538{ 540{
541 int ret;
542
539 /* Are we from a system call? */ 543 /* Are we from a system call? */
540 if (regs->orig_eax >= 0) { 544 if (regs->orig_eax >= 0) {
541 /* If so, check system call restarting.. */ 545 /* If so, check system call restarting.. */
@@ -569,17 +573,19 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
569 573
570 /* Set up the stack frame */ 574 /* Set up the stack frame */
571 if (ka->sa.sa_flags & SA_SIGINFO) 575 if (ka->sa.sa_flags & SA_SIGINFO)
572 setup_rt_frame(sig, ka, info, oldset, regs); 576 ret = setup_rt_frame(sig, ka, info, oldset, regs);
573 else 577 else
574 setup_frame(sig, ka, oldset, regs); 578 ret = setup_frame(sig, ka, oldset, regs);
575 579
576 if (!(ka->sa.sa_flags & SA_NODEFER)) { 580 if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
577 spin_lock_irq(&current->sighand->siglock); 581 spin_lock_irq(&current->sighand->siglock);
578 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask); 582 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
579 sigaddset(&current->blocked,sig); 583 sigaddset(&current->blocked,sig);
580 recalc_sigpending(); 584 recalc_sigpending();
581 spin_unlock_irq(&current->sighand->siglock); 585 spin_unlock_irq(&current->sighand->siglock);
582 } 586 }
587
588 return ret;
583} 589}
584 590
585/* 591/*
@@ -622,8 +628,7 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
622 } 628 }
623 629
624 /* Whee! Actually deliver the signal. */ 630 /* Whee! Actually deliver the signal. */
625 handle_signal(signr, &info, &ka, oldset, regs); 631 return handle_signal(signr, &info, &ka, oldset, regs);
626 return 1;
627 } 632 }
628 633
629 no_signal: 634 no_signal: