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 <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/kernel/signal.c b/kernel/signal.c
index 20931a892ace10e1c0a8d17620283b47d4a41eac..d7d1adf735f44eaae535591e4af571f5d8946758 100644 (file)
--- 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;
 
        /*