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Date:   Thu, 30 May 2019 16:06:02 +0800
From:   Gen Zhang <blackgod016574@gmail.com>
To:     paul@paul-moore.com, sds@tycho.nsa.gov, eparis@parisplace.org,
        ccross@android.com
Cc:     selinux@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Subject: [PATCH] hooks: fix a missing-check bug in selinux_add_mnt_opt()
Message-ID: <20190530080602.GA3600@zhanggen-UX430UQ>
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User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
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In selinux_add_mnt_opt(), 'val' is allcoted by kmemdup_nul(). It returns
NULL when fails. So 'val' should be checked.

Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
---
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3ec702c..4797c63 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1052,8 +1052,11 @@ static int selinux_add_mnt_opt(const char *option, const char *val, int len,
 	if (token == Opt_error)
 		return -EINVAL;
 
-	if (token != Opt_seclabel)
-		val = kmemdup_nul(val, len, GFP_KERNEL);
+	if (token != Opt_seclabel) {
+			val = kmemdup_nul(val, len, GFP_KERNEL);
+			if (!val)
+				return -ENOMEM;
+	}
 	rc = selinux_add_opt(token, val, mnt_opts);
 	if (unlikely(rc)) {
 		kfree(val);