linux-kernel - [PATCH AUTOSEL for 4.9 019/293] KEYS: put keyring if install_session_keyring_to

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Message-ID: <20180409002239.163177-19-alexander.levin@microsoft.com>
Date:   Mon, 9 Apr 2018 00:23:04 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Eric Biggers <ebiggers@...gle.com>,
        David Howells <dhowells@...hat.com>,
        James Morris <james.l.morris@...cle.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 019/293] KEYS: put keyring if
 install_session_keyring_to_cred() fails

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

[ Upstream commit d636bd9f12a66ea3775c9fabbf3f8e118253467a ]

In join_session_keyring(), if install_session_keyring_to_cred() were to
fail, we would leak the keyring reference, just like in the bug fixed by
commit 23567fd052a9 ("KEYS: Fix keyring ref leak in
join_session_keyring()").  Fortunately this cannot happen currently, but
we really should be more careful.  Do this by adding and using a new
error label at which the keyring reference is dropped.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: James Morris <james.l.morris@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 security/keys/process_keys.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 2d35d71d7d9a..88c94e6c2158 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -810,15 +810,14 @@ long join_session_keyring(const char *name)
 		ret = PTR_ERR(keyring);
 		goto error2;
 	} else if (keyring == new->session_keyring) {
-		key_put(keyring);
 		ret = 0;
-		goto error2;
+		goto error3;
 	}
 
 	/* we've got a keyring - now to install it */
 	ret = install_session_keyring_to_cred(new, keyring);
 	if (ret < 0)
-		goto error2;
+		goto error3;
 
 	commit_creds(new);
 	mutex_unlock(&key_session_mutex);
@@ -828,6 +827,8 @@ long join_session_keyring(const char *name)
 okay:
 	return ret;
 
+error3:
+	key_put(keyring);
 error2:
 	mutex_unlock(&key_session_mutex);
 error:
-- 
2.15.1