m68k: If we fail to set sigframe up, just leave regs alone...

Same principle as with the previous patch - do not destroy the
state if sigframe setup fails.  Incidentally, it's actually
_less_ work - we don't need to go through adjust_stack dance
on failure if we don't touch regs->stkadj until we know we'd
written sigframe out.

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

1 files changed, 30 insertions, 14 deletions

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a6dd61418e76..16ea319d1ed5 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -761,10 +761,8 @@ static int setup_frame (int sig, struct k_sigaction *ka,
 
         frame = get_sigframe(ka, regs, sizeof(*frame) + fsize);
 
-        if (fsize) {
+        if (fsize)
                 err |= copy_to_user (frame + 1, regs + 1, fsize);
-                regs->stkadj = fsize;
-        }
 
         err |= __put_user((current_thread_info()->exec_domain
                            && current_thread_info()->exec_domain->signal_invmap
@@ -794,11 +792,21 @@ static int setup_frame (int sig, struct k_sigaction *ka,
 
         push_cache ((unsigned long) &frame->retcode);
 
-        /* Set up registers for signal handler */
+        /*
+         * Set up registers for signal handler.  All the state we are about
+         * to destroy is successfully copied to sigframe.
+         */
         wrusp ((unsigned long) frame);
         regs->pc = (unsigned long) ka->sa.sa_handler;
 
-adjust_stack:
+        /*
+         * This is subtle; if we build more than one sigframe, all but the
+         * first one will see frame format 0 and have fsize == 0, so we won't
+         * screw stkadj.
+         */
+        if (fsize)
+                regs->stkadj = fsize;
+
         /* Prepare to skip over the extra stuff in the exception frame.  */
         if (regs->stkadj) {
                 struct pt_regs *tregs =
@@ -813,11 +821,11 @@ adjust_stack:
                 tregs->pc = regs->pc;
                 tregs->sr = regs->sr;
         }
-        return err;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
-        goto adjust_stack;
+        return err;
 }
 
 static int setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
@@ -837,10 +845,8 @@ static int setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
 
         frame = get_sigframe(ka, regs, sizeof(*frame));
 
-        if (fsize) {
+        if (fsize)
                 err |= copy_to_user (&frame->uc.uc_extra, regs + 1, fsize);
-                regs->stkadj = fsize;
-        }
 
         err |= __put_user((current_thread_info()->exec_domain
                            && current_thread_info()->exec_domain->signal_invmap
@@ -882,11 +888,21 @@ static int setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
 
         push_cache ((unsigned long) &frame->retcode);
 
-        /* Set up registers for signal handler */
+        /*
+         * Set up registers for signal handler.  All the state we are about
+         * to destroy is successfully copied to sigframe.
+         */
         wrusp ((unsigned long) frame);
         regs->pc = (unsigned long) ka->sa.sa_handler;
 
-adjust_stack:
+        /*
+         * This is subtle; if we build more than one sigframe, all but the
+         * first one will see frame format 0 and have fsize == 0, so we won't
+         * screw stkadj.
+         */
+        if (fsize)
+                regs->stkadj = fsize;
+
         /* Prepare to skip over the extra stuff in the exception frame.  */
         if (regs->stkadj) {
                 struct pt_regs *tregs =
@@ -901,11 +917,11 @@ adjust_stack:
                 tregs->pc = regs->pc;
                 tregs->sr = regs->sr;
         }
-        return err;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
-        goto adjust_stack;
+        return err;
 }
 
 static inline void