audit: Fix check of return value of strnlen_user()

strnlen_user() returns 0 when it hits fault, not -1. Fix the test in
audit_log_single_execve_arg(). Luckily this shouldn't ever happen unless
there's a kernel bug so it's mostly a cosmetic fix.

CC: Paul Moore <pmoore@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <pmoore@redhat.com>

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d81424fbec3aaf89750fc51a511bd385078270f3..f6bc31e7dca9bd76e5579ec6786a97f70ccedb6d 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1021,7 +1021,7 @@ static int audit_log_single_execve_arg(struct audit_context *context,
         * for strings that are too long, we should not have created
         * any.
         */
-       if (unlikely((len == -1) || len > MAX_ARG_STRLEN - 1)) {
+       if (unlikely((len == 0) || len > MAX_ARG_STRLEN - 1)) {
                WARN_ON(1);
                send_sig(SIGKILL, current, 0);
                return -1;