From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753836AbcCGWwD (ORCPT ); Mon, 7 Mar 2016 17:52:03 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:38420 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753602AbcCGWvi (ORCPT ); Mon, 7 Mar 2016 17:51:38 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: David Howells , James Morris , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 005/273] KEYS: Fix keyring ref leak in join_session_keyring() Date: Mon, 7 Mar 2016 14:46:36 -0800 Message-Id: <1457391064-6660-6-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457391064-6660-1-git-send-email-kamal@canonical.com> References: <1457391064-6660-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Yevgeny Pats commit 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2 upstream. This fixes CVE-2016-0728. If a thread is asked to join as a session keyring the keyring that's already set as its session, we leak a keyring reference. This can be tested with the following program: #include #include #include #include int main(int argc, const char *argv[]) { int i = 0; key_serial_t serial; serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, "leaked-keyring"); if (serial < 0) { perror("keyctl"); return -1; } if (keyctl(KEYCTL_SETPERM, serial, KEY_POS_ALL | KEY_USR_ALL) < 0) { perror("keyctl"); return -1; } for (i = 0; i < 100; i++) { serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, "leaked-keyring"); if (serial < 0) { perror("keyctl"); return -1; } } return 0; } If, after the program has run, there something like the following line in /proc/keys: 3f3d898f I--Q--- 100 perm 3f3f0000 0 0 keyring leaked-keyring: empty with a usage count of 100 * the number of times the program has been run, then the kernel is malfunctioning. If leaked-keyring has zero usages or has been garbage collected, then the problem is fixed. Reported-by: Yevgeny Pats Signed-off-by: David Howells Acked-by: Don Zickus Acked-by: Prarit Bhargava Acked-by: Jarod Wilson Signed-off-by: James Morris Signed-off-by: Kamal Mostafa --- security/keys/process_keys.c | 1 + 1 file changed, 1 insertion(+) diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index bd536cb..db91639 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -794,6 +794,7 @@ 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; } -- 2.7.0