diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index a9c516362170..61e734baa332 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -923,7 +923,7 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
 	}
 
 	ret = sscanf(rule, "%d", &catlen);
-	if (ret != 1 || catlen > SMACK_CIPSO_MAXCATNUM)
+	if (ret != 1 || catlen < 0 || catlen > SMACK_CIPSO_MAXCATNUM)
 		goto out;
 
 	if (format == SMK_FIXED24_FMT &&