linux-kernel - [PATCH 3.2 22/94] KEYS: fix key refcount leak in keyctl_read

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Date:   Thu, 28 Dec 2017 16:59:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David Howells" <dhowells@...hat.com>,
        "Eric Biggers" <ebiggers@...gle.com>
Subject: [PATCH 3.2 22/94] KEYS: fix key refcount leak in keyctl_read_key()

3.2.97-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>

commit 7fc0786d956d9e59b68d282be9b156179846ea3d upstream.

In keyctl_read_key(), if key_permission() were to return an error code
other than EACCES, we would leak a the reference to the key.  This can't
actually happen currently because key_permission() can only return an
error code other than EACCES if security_key_permission() does, only
SELinux and Smack implement that hook, and neither can return an error
code other than EACCES.  But it should still be fixed, as it is a bug
waiting to happen.

Fixes: 29db91906340 ("[PATCH] Keys: Add LSM hooks for key management [try #3]")
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 security/keys/keyctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -684,7 +684,7 @@ long keyctl_read_key(key_serial_t keyid,
 	if (ret == 0)
 		goto can_read_key;
 	if (ret != -EACCES)
-		goto error;
+		goto error2;

 	/* we can't; see if it's searchable from this process's keyrings
 	 * - we automatically take account of the fact that it may be