From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752649Ab3KTKoQ (ORCPT ); Wed, 20 Nov 2013 05:44:16 -0500 Received: from ra.se.axis.com ([195.60.68.13]:58587 "EHLO ra.se.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752328Ab3KTKoO (ORCPT ); Wed, 20 Nov 2013 05:44:14 -0500 Date: Wed, 20 Nov 2013 11:44:12 +0100 From: Jesper Nilsson To: Andrew Morton , Davidlohr Bueso , Rik van Riel , Michel Lespinasse , Al Viro , linux-kernel@vger.kernel.org Subject: [PATCH] ipc,shm: Correct error return value in shmctl (SHM_UNLOCK) Message-ID: <20131120104411.GA15831@axis.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 2caacaa82a51b78fc0c800e206473874094287ed restructured the ipc shm to shorten critical region, but introduced a path where the return value could be -EPERM, even if the operation actually was performed. Before the commit, the err return value was reset by the return value from security_shm_shmctl() after the if (!ns_capable(...)) statement. Now, we still exit the if statement with err set to -EPERM, and in the case of SHM_UNLOCK, it is not reset at all, and used as the return value from shmctl. To fix this, we only set err when errors occur, leaving the fallthrough case alone. Signed-off-by: Jesper Nilsson Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Rik van Riel Cc: Michel Lespinasse Cc: Al Viro Cc: stable@vger.kernel.org --- ipc/shm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index d697396..4076f9e 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -974,12 +974,15 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf) ipc_lock_object(&shp->shm_perm); if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) { kuid_t euid = current_euid(); - err = -EPERM; if (!uid_eq(euid, shp->shm_perm.uid) && - !uid_eq(euid, shp->shm_perm.cuid)) + !uid_eq(euid, shp->shm_perm.cuid)) { + err = -EPERM; goto out_unlock0; - if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) + } + if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) { + err = -EPERM; goto out_unlock0; + } } shm_file = shp->shm_file; -- 1.8.4 /^JN - Jesper Nilsson -- Jesper Nilsson -- jesper.nilsson@axis.com