m68k: Don't lose state if sigframe setup fails

If we'd failed in setup_frame(), we've no place to store
the original sigmask.  It's not an unrecoverable situation -
we raise SIGSEGV, but that SIGSEGV might be successfully
handled (e.g. on altstack).  In that case we really don't
want sa_mask of original signal permanently slapped on
the set of blocked signals.

Standard solution: have setup_frame()/setup_rt_frame()
report failure and don't mess with the signal-related
state if that has happened...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

1 files changed, 12 insertions, 7 deletions

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a18b251fe593..a6dd61418e76 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -743,7 +743,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
         return (void __user *)((usp - frame_size) & -8UL);
 }
 
-static void setup_frame (int sig, struct k_sigaction *ka,
+static int setup_frame (int sig, struct k_sigaction *ka,
                          sigset_t *set, struct pt_regs *regs)
 {
         struct sigframe __user *frame;
@@ -813,14 +813,14 @@ adjust_stack:
                 tregs->pc = regs->pc;
                 tregs->sr = regs->sr;
         }
-        return;
+        return err;
 
 give_sigsegv:
         force_sigsegv(sig, current);
         goto adjust_stack;
 }
 
-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;
@@ -901,7 +901,7 @@ adjust_stack:
                 tregs->pc = regs->pc;
                 tregs->sr = regs->sr;
         }
-        return;
+        return err;
 
 give_sigsegv:
         force_sigsegv(sig, current);
@@ -963,6 +963,7 @@ static void
 handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
               sigset_t *oldset, struct pt_regs *regs)
 {
+        int err;
         /* are we from a system call? */
         if (regs->orig_d0 >= 0)
                 /* If so, check system call restarting.. */
@@ -970,9 +971,12 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
 
         /* set up the stack frame */
         if (ka->sa.sa_flags & SA_SIGINFO)
-                setup_rt_frame(sig, ka, info, oldset, regs);
+                err = setup_rt_frame(sig, ka, info, oldset, regs);
         else
-                setup_frame(sig, ka, oldset, regs);
+                err = setup_frame(sig, ka, oldset, regs);
+
+        if (err)
+                return;
 
         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
         if (!(ka->sa.sa_flags & SA_NODEFER))
@@ -983,6 +987,8 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
                 regs->sr &= ~0x8000;
                 send_sig(SIGTRAP, current, 1);
         }
+
+        clear_thread_flag(TIF_RESTORE_SIGMASK);
 }
 
 /*
@@ -1008,7 +1014,6 @@ asmlinkage void do_signal(struct pt_regs *regs)
         if (signr > 0) {
                 /* Whee!  Actually deliver the signal.  */
                 handle_signal(signr, &ka, &info, oldset, regs);
-                clear_thread_flag(TIF_RESTORE_SIGMASK);
                 return;
         }