signal: simplify rt_sigaction()

The goto is not needed and does not add any clarity.  Simply return
-EINVAL on unexpected sigset_t struct size directly.

Link: http://lkml.kernel.org/r/20180602103653.18181-6-christian@brauner.io
Signed-off-by: Christian Brauner <christian@brauner.io>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Morris <james.morris@microsoft.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/signal.c b/kernel/signal.c
index 10918c7..adeee50 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3648,25 +3648,23 @@ SYSCALL_DEFINE4(rt_sigaction, int, sig,
                size_t, sigsetsize)
 {
        struct k_sigaction new_sa, old_sa;
-       int ret = -EINVAL;
+       int ret;
 
        /* XXX: Don't preclude handling different sized sigset_t's.  */
        if (sigsetsize != sizeof(sigset_t))
-               goto out;
+               return -EINVAL;
 
-       if (act) {
-               if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
-                       return -EFAULT;
-       }
+       if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
+               return -EFAULT;
 
        ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
+       if (ret)
+               return ret;
 
-       if (!ret && oact) {
-               if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
-                       return -EFAULT;
-       }
-out:
-       return ret;
+       if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
+               return -EFAULT;
+
+       return 0;
 }
 #ifdef CONFIG_COMPAT
 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,