sparc: Fix SA_ONSTACK signal handling.

[deliverable/linux.git] / arch / sparc64 / kernel / signal.c

diff --git a/arch/sparc64/kernel/signal.c b/arch/sparc64/kernel/signal.c
index 45d6bf632daa6a6e4fe5c6826629c3ff9eb1f732..07c0443ea3f545f6ad97bc7185b5eb9d3ce8a78d 100644 (file)
--- a/arch/sparc64/kernel/signal.c
+++ b/arch/sparc64/kernel/signal.c
@@ -376,16 +376,29 @@ save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
 
 static inline void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, unsigned long framesize)
 {
-       unsigned long sp;
+       unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS;
 
-       sp = regs->u_regs[UREG_FP] + STACK_BIAS;
+       /*
+        * If we are on the alternate signal stack and would overflow it, don't.
+        * Return an always-bogus address instead so we will die with SIGSEGV.
+        */
+       if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
+               return (void __user *) -1L;
 
        /* This is the X/Open sanctioned signal stack switching.  */
        if (ka->sa.sa_flags & SA_ONSTACK) {
-               if (!on_sig_stack(sp) &&
-                   !((current->sas_ss_sp + current->sas_ss_size) & 7))
+               if (sas_ss_flags(sp) == 0)
                        sp = current->sas_ss_sp + current->sas_ss_size;
        }
+
+       /* Always align the stack frame.  This handles two cases.  First,
+        * sigaltstack need not be mindful of platform specific stack
+        * alignment.  Second, if we took this signal because the stack
+        * is not aligned properly, we'd like to take the signal cleanly
+        * and report that.
+        */
+       sp &= ~7UL;
+
        return (void __user *)(sp - framesize);
 }