Re: [syzbot] Re: KASAN: slab-out-of-bounds Read in led_tg_check()

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Subject: Re: KASAN: slab-out-of-bounds Read in led_tg_check()
Author: dmantipov@xxxxxxxxx

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git dd7207838d38780b51e4690ee508ab2d5057e099

diff --git a/net/netfilter/xt_LED.c b/net/netfilter/xt_LED.c
index f7b0286d106a..8a80fd76fe45 100644
--- a/net/netfilter/xt_LED.c
+++ b/net/netfilter/xt_LED.c
@@ -96,7 +96,9 @@ static int led_tg_check(const struct xt_tgchk_param *par)
 	struct xt_led_info_internal *ledinternal;
 	int err;
 
-	if (ledinfo->id[0] == '\0')
+	/* Bail out if empty string or not a string at all. */
+	if (ledinfo->id[0] == '\0' ||
+	    !memchr(ledinfo->id, '\0', sizeof(ledinfo->id)))
 		return -EINVAL;
 
 	mutex_lock(&xt_led_mutex);