linux-kernel - [PATCH v2 1/1] selinux: fix double free

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Message-Id: <20200610215713.5319-2-trix@redhat.com>
Date:   Wed, 10 Jun 2020 14:57:13 -0700
From:   trix@...hat.com
To:     paul@...l-moore.com, stephen.smalley.work@...il.com,
        eparis@...isplace.org, omosnace@...hat.com, jeffv@...gle.com,
        rgb@...hat.com
Cc:     selinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tom Rix <trix@...hat.com>
Subject: [PATCH v2 1/1] selinux: fix double free

From: Tom Rix <trix@...hat.com>

Clang's static analysis tool reports these double free memory errors.

security/selinux/ss/services.c:2987:4: warning: Attempt to free released memory [unix.Malloc]
                        kfree(bnames[i]);
                        ^~~~~~~~~~~~~~~~
security/selinux/ss/services.c:2990:2: warning: Attempt to free released memory [unix.Malloc]
        kfree(bvalues);
        ^~~~~~~~~~~~~~

So improve the security_get_bools error handling by freeing these variables
and setting their return pointers to NULL and the return len to 0

Signed-off-by: Tom Rix <trix@...hat.com>
---
 security/selinux/ss/services.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 313919bd42f8..ef0afd878bfc 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2888,8 +2888,12 @@ int security_get_bools(struct selinux_state *state,
 	if (*names) {
 		for (i = 0; i < *len; i++)
 			kfree((*names)[i]);
+		kfree(*names);
 	}
 	kfree(*values);
+	*len = 0;
+	*names = NULL;
+	*values = NULL;
 	goto out;
 }
 
-- 
2.18.1