microblaze: fix signal masking

There are a couple of problems with the current signal code,

1. If we failed to setup the signal stack frame then we should not be
   masking any signals.

2. ka->sa.sa_mask is only added to the current blocked signals list if
   SA_NODEFER is set in ka->sa.sa_flags.  If we successfully setup the
   signal frame and are going to run the handler then we must honour
   sa_mask.

Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 18 insertions, 13 deletions

diff --git a/arch/microblaze/kernel/signal.c b/arch/microblaze/kernel/signal.c
index 9e749c032af8..f2c13d5a6261 100644
--- a/arch/microblaze/kernel/signal.c
+++ b/arch/microblaze/kernel/signal.c
@@ -169,7 +169,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
         return (void __user *)((sp - frame_size) & -8UL);
 }
 
-static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                         sigset_t *set, struct pt_regs *regs)
 {
         struct rt_sigframe __user *frame;
@@ -267,10 +267,11 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 current->comm, current->pid, frame, regs->pc);
 #endif
 
-        return;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
+        return -EFAULT;
 }
 
 /* Handle restarting system calls */
@@ -314,21 +315,25 @@ static int
 handle_signal(unsigned long sig, struct k_sigaction *ka,
                 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 {
+        int ret;
+
         /* Set up the stack frame */
         if (ka->sa.sa_flags & SA_SIGINFO)
-                setup_rt_frame(sig, ka, info, oldset, regs);
+                ret = setup_rt_frame(sig, ka, info, oldset, regs);
         else
-                setup_rt_frame(sig, ka, NULL, oldset, regs);
+                ret = setup_rt_frame(sig, ka, NULL, oldset, regs);
+
+        if (ret)
+                return ret;
 
-        if (!(ka->sa.sa_flags & SA_NODEFER)) {
-                spin_lock_irq(&current->sighand->siglock);
-                sigorsets(&current->blocked,
-                                &current->blocked, &ka->sa.sa_mask);
+        spin_lock_irq(&current->sighand->siglock);
+        sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
+        if (!(ka->sa.sa_flags & SA_NODEFER))
                 sigaddset(&current->blocked, sig);
-                recalc_sigpending();
-                spin_unlock_irq(&current->sighand->siglock);
-        }
-        return 1;
+        recalc_sigpending();
+        spin_unlock_irq(&current->sighand->siglock);
+
+        return 0;
 }
 
 /*
@@ -369,7 +374,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
                 /* Whee! Actually deliver the signal. */
                 if (in_syscall)
                         handle_restart(regs, &ka, 1);
-                if (handle_signal(signr, &ka, &info, oldset, regs)) {
+                if (!handle_signal(signr, &ka, &info, oldset, regs)) {
                         /*
                          * A signal was successfully delivered; the saved
                          * sigmask will have been stored in the signal frame,