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authorDavid S. Miller <davem@davemloft.net>2008-05-07 18:54:05 -0700
committerDavid S. Miller <davem@davemloft.net>2008-05-07 18:54:05 -0700
commitdc5dc7e6d71ca9fd1ea01a1418150af3b2937489 (patch)
tree0071bfb3de792bc28354bfc30f7dac12e69e139a /arch/sparc
parent1e38c126c9252b612697e34f43b1b3371c8ee31d (diff)
sparc: Fix SA_ONSTACK signal handling.
We need to be more liberal about the alignment of the buffer given to us by sigaltstack(). The user should not need to be mindful of all of the alignment constraints we have for the stack frame. This mirrors how we handle this situation in clone() as well. Also, we align the stack even in non-SA_ONSTACK cases so that signals due to bad stack alignment can be delivered properly. This makes such errors easier to debug and recover from. Finally, add the sanity check x86 has to make sure we won't overflow the signal stack. This fixes glibc testcases nptl/tst-cancel20.c and nptl/tst-cancelx20.c Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc')
-rw-r--r--arch/sparc/kernel/signal.c20
1 files changed, 17 insertions, 3 deletions
diff --git a/arch/sparc/kernel/signal.c b/arch/sparc/kernel/signal.c
index 3c312290c3c..368157926d2 100644
--- a/arch/sparc/kernel/signal.c
+++ b/arch/sparc/kernel/signal.c
@@ -245,15 +245,29 @@ static inline int invalid_frame_pointer(void __user *fp, int fplen)
static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
{
- unsigned long sp;
+ unsigned long sp = regs->u_regs[UREG_FP];
- sp = regs->u_regs[UREG_FP];
+ /*
+ * 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 (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);
}