[PATCH 4.19 103/168] Smack: prevent underflow in smk_set_cipso()

Greg Kroah-Hartman
2020-08-17T17:42:55Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 42a2df3e829f3c5562090391b33714b2e2e5ad4a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 981f582539acf..accd3846f1e3e 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -912,7 +912,7 @@ 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;
--
2.25.1