[S390] Protect against sigaltstack wraparound.
This is just a port of 83bd01024b1fdfc41d9b758e5669e80fca72df66
"x86: protect against sigaltstack wraparound".
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index a5692c4..ae2f2d3 100644
--- a/arch/s390/kernel/compat_signal.c
+++ b/arch/s390/kernel/compat_signal.c
@@ -428,6 +428,10 @@
/* Default to using normal stack */
sp = (unsigned long) A(regs->gprs[15]);
+ /* Overflow on alternate signal stack gives SIGSEGV. */
+ if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
+ return (void __user *) -1UL;
+
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (! sas_ss_flags(sp))
@@ -461,6 +465,9 @@
if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe32)))
goto give_sigsegv;
+ if (frame == (void __user *) -1UL)
+ goto give_sigsegv;
+
if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE32))
goto give_sigsegv;
@@ -514,6 +521,9 @@
if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe32)))
goto give_sigsegv;
+ if (frame == (void __user *) -1UL)
+ goto give_sigsegv;
+
if (copy_siginfo_to_user32(&frame->info, info))
goto give_sigsegv;