From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 23 Jul 2020 15:23:05 +0000 (+0300)
Subject: Smack: prevent underflow in smk_set_cipso()
X-Git-Tag: v5.9-rc1~127^2
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=42a2df3e829f3c5562090391b33714b2e2e5ad4a;p=linux-2.6-block.git

Smack: prevent underflow in smk_set_cipso()

We have an upper bound on "maplevel" but forgot to check for negative
values.

Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 2bae1fc493d1..9c4308077574 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -884,7 +884,7 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
 	}
 
 	ret = sscanf(rule, "%d", &maplevel);
-	if (ret != 1 || maplevel > SMACK_CIPSO_MAXLEVEL)
+	if (ret != 1 || maplevel < 0 || maplevel > SMACK_CIPSO_MAXLEVEL)
 		goto out;
 
 	rule += SMK_DIGITLEN;