From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757318Ab2HOUhL (ORCPT ); Wed, 15 Aug 2012 16:37:11 -0400 Received: from mail1.windriver.com ([147.11.146.13]:62749 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756251Ab2HOTtM (ORCPT ); Wed, 15 Aug 2012 15:49:12 -0400 From: Paul Gortmaker To: , CC: David Howells , Linus Torvalds , Paul Gortmaker Subject: [v2.6.34-stable 019/165] KEYS: Fix a NULL pointer deref in the user-defined key type Date: Wed, 15 Aug 2012 15:46:03 -0400 Message-ID: <1345060109-9187-20-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.12.rc2 In-Reply-To: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 9f35a33b8d06263a165efe3541d9aa0cdbd70b3b upstream. Fix a NULL pointer deref in the user-defined key type whereby updating a negative key into a fully instantiated key will cause an oops to occur when the code attempts to free the non-existent old payload. This results in an oops that looks something like the following: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [] __call_rcu+0x11/0x13e PGD 3391d067 PUD 3894a067 PMD 0 Oops: 0002 [#1] SMP CPU 1 Pid: 4354, comm: keyctl Not tainted 3.1.0-fsdevel+ #1140 /DG965RY RIP: 0010:[] [] __call_rcu+0x11/0x13e RSP: 0018:ffff88003d591df8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000006e RDX: ffffffff8161d0c0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88003d591e18 R08: 0000000000000000 R09: ffffffff8152fa6c R10: 0000000000000000 R11: 0000000000000300 R12: ffff88003b8f9538 R13: ffffffff8161d0c0 R14: ffff88003b8f9d50 R15: ffff88003c69f908 FS: 00007f97eb18c720(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000003d47a000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process keyctl (pid: 4354, threadinfo ffff88003d590000, task ffff88003c78a040) Stack: ffff88003e0ffde0 ffff88003b8f9538 0000000000000001 ffff88003b8f9d50 ffff88003d591e28 ffffffff810860f0 ffff88003d591e68 ffffffff8117bfea ffff88003d591e68 ffffffff00000000 ffff88003e0ffde1 ffff88003e0ffde0 Call Trace: [] call_rcu_sched+0x10/0x12 [] user_update+0x8d/0xa2 [] key_create_or_update+0x236/0x270 [] sys_add_key+0x123/0x17e [] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells Acked-by: Jeff Layton Acked-by: Neil Horman Acked-by: Steve Dickson Acked-by: James Morris Signed-off-by: Linus Torvalds [PG: pre-3.0 kernels dont have kfree_rcu, so tweak accordingly] Signed-off-by: Paul Gortmaker --- security/keys/user_defined.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c index e9aa079..d6781b9 100644 --- a/security/keys/user_defined.c +++ b/security/keys/user_defined.c @@ -119,7 +119,8 @@ int user_update(struct key *key, const void *data, size_t datalen) key->expiry = 0; } - call_rcu(&zap->rcu, user_update_rcu_disposal); + if (zap) + call_rcu(&zap->rcu, user_update_rcu_disposal); error: return ret; -- 1.7.12.rc2