[PATCH] x86_64: never block forced SIGSEGV

This is the x86_64 version of the signal fix I just posted for i386.

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>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 7 deletions

diff --git a/arch/x86_64/ia32/ia32_signal.c b/arch/x86_64/ia32/ia32_signal.c
index fbd09b5126ce..66e2821533db 100644
--- a/arch/x86_64/ia32/ia32_signal.c
+++ b/arch/x86_64/ia32/ia32_signal.c
@@ -428,8 +428,8 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
         return (void __user *)((rsp - frame_size) & -8UL);
 }
 
-void ia32_setup_frame(int sig, struct k_sigaction *ka,
-                        compat_sigset_t *set, struct pt_regs * regs)
+int ia32_setup_frame(int sig, struct k_sigaction *ka,
+                     compat_sigset_t *set, struct pt_regs * regs)
 {
         struct sigframe __user *frame;
         int err = 0;
@@ -514,14 +514,15 @@ void ia32_setup_frame(int sig, struct k_sigaction *ka,
                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-        return;
+        return 1;
 
 give_sigsegv:
         force_sigsegv(sig, current);
+        return 0;
 }
 
-void ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
-                           compat_sigset_t *set, struct pt_regs * regs)
+int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+                        compat_sigset_t *set, struct pt_regs * regs)
 {
         struct rt_sigframe __user *frame;
         int err = 0;
@@ -613,9 +614,9 @@ void ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-        return;
+        return 1;
 
 give_sigsegv:
         force_sigsegv(sig, current);
+        return 0;
 }
-