[PATCH] do_sigaction: cleanup ->sa_mask manipulation

Clear unblockable signals beforehand.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/sched.h

@@ -1075,7 +1075,7 @@ extern struct sigqueue *sigqueue_alloc(void);
 extern void sigqueue_free(struct sigqueue *);
 extern int send_sigqueue(int, struct sigqueue *,  struct task_struct *);
 extern int send_group_sigqueue(int, struct sigqueue *,  struct task_struct *);
-extern int do_sigaction(int, const struct k_sigaction *, struct k_sigaction *);
+extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
 extern int do_sigaltstack(const stack_t __user *, stack_t __user *, unsigned long);
 
 /* These can be the second arg to send_sig_info/send_group_sig_info.  */

kernel/signal.c

@@ -2335,7 +2335,7 @@ sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
 }
 
 int
-do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
+do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
 {
 	struct k_sigaction *k;
 
@@ -2358,6 +2358,8 @@ do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
 		*oact = *k;
 
 	if (act) {
+		sigdelsetmask(&act->sa.sa_mask,
+			      sigmask(SIGKILL) | sigmask(SIGSTOP));
 		/*
 		 * POSIX 3.3.1.3:
 		 *  "Setting a signal action to SIG_IGN for a signal that is
@@ -2383,8 +2385,6 @@ do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
 			read_lock(&tasklist_lock);
 			spin_lock_irq(&t->sighand->siglock);
 			*k = *act;
-			sigdelsetmask(&k->sa.sa_mask,
-				      sigmask(SIGKILL) | sigmask(SIGSTOP));
 			rm_from_queue(sigmask(sig), &t->signal->shared_pending);
 			do {
 				rm_from_queue(sigmask(sig), &t->pending);
@@ -2397,8 +2397,6 @@ do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
 		}
 
 		*k = *act;
-		sigdelsetmask(&k->sa.sa_mask,
-			      sigmask(SIGKILL) | sigmask(SIGSTOP));
 	}
 
 	spin_unlock_irq(&current->sighand->siglock);