linux-kernel - [PATCH] KEYS: fix key refcount leak in keyctl_read

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Message-Id: <20170918183631.113991-1-ebiggers3@gmail.com>
Date:   Mon, 18 Sep 2017 11:36:31 -0700
From:   Eric Biggers <ebiggers3@...il.com>
To:     keyrings@...r.kernel.org
Cc:     David Howells <dhowells@...hat.com>,
        Michael Halcrow <mhalcrow@...gle.com>,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH] KEYS: fix key refcount leak in keyctl_read_key()

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

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>
---
 security/keys/keyctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 552e4460683b..365ff85d7e27 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -776,7 +776,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 	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
-- 
2.14.1.690.gbb1197296e-goog