signal: Never allocate siginfo for SIGKILL or SIGSTOP

The SIGKILL and SIGSTOP signals are never delivered to userspace so queued siginfo for these signals can never be observed. Therefore remove the chance of failure by never even attempting to allocate siginfo in those cases. Reviewed-by: Thomas Gleixner <[email protected]> Signed-off-by: "Eric W. Biederman" <[email protected]>
kawasaki · Sep 11, 2018 · f149b31 · f149b31
1 parent 0351505
commit f149b31
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/kernel/signal.c b/kernel/signal.c
@@ -1054,10 +1054,11 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 
 	result = TRACE_SIGNAL_DELIVERED;
 	/*
-	 * fast-pathed signals for kernel-internal things like SIGSTOP
-	 * or SIGKILL.
+	 * Skip useless siginfo allocation for SIGKILL SIGSTOP,
+	 * and kernel threads.
 	 */
-	if ((info == SEND_SIG_FORCED) || (t->flags & PF_KTHREAD))
+	if ((info == SEND_SIG_FORCED) ||
+	    sig_kernel_only(sig) || (t->flags & PF_KTHREAD))
 		goto out_set;
 
 	/*