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[5.8,303/464] Smack: prevent underflow in smk_set_cipso()

Message ID 20200817143848.319245665@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Aug. 17, 2020, 3:14 p.m. UTC 
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(-)
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Patch

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 2bae1fc493d16..9c4308077574c 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;