[S390] Protect against sigaltstack wraparound.

[deliverable/linux.git] / arch / s390 / kernel / signal.c

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4449bf32cbf1e976e414518cee77998587ba18a3..8c92191949c2f6843cd6b552cadbf9e2f4b8931e 100644 (file)
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -235,6 +235,10 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
        /* Default to using normal stack */
        sp = 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))
@@ -270,6 +274,9 @@ static int setup_frame(int sig, struct k_sigaction *ka,
        if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
                goto give_sigsegv;
 
+       if (frame == (void __user *) -1UL)
+               goto give_sigsegv;
+
        if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
                goto give_sigsegv;
 
@@ -327,6 +334,9 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
        if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
                goto give_sigsegv;
 
+       if (frame == (void __user *) -1UL)
+               goto give_sigsegv;
+
        if (copy_siginfo_to_user(&frame->info, info))
                goto give_sigsegv;