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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [PATCH 2/2] Smack: prevent underflow in smk_set_cipso()
Date: Thu, 23 Jul 2020 18:23:05 +0300	[thread overview]
Message-ID: <20200723152305.GB302005@mwanda> (raw)
In-Reply-To: <000000000000d282bd05ab0bf532@google.com>

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>
---
 security/smack/smackfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 81c6ceeaa4f9..7675305511ef 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;
-- 
2.27.0


      parent reply	other threads:[~2020-07-23 15:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 18:32 KASAN: slab-out-of-bounds Read in vsscanf (2) syzbot
2020-07-23 15:22 ` [PATCH 1/2] Smack: fix another vsscanf out of bounds Dan Carpenter
2020-07-23 16:38   ` Casey Schaufler
2020-07-23 15:23 ` Dan Carpenter [this message]

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