Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934311AbaLLGWn (ORCPT ); Fri, 12 Dec 2014 01:22:43 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51766 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759472AbaLLGRO (ORCPT ); Fri, 12 Dec 2014 01:17:14 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Chao Yu" , "Tyler Hicks" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 048/164] ecryptfs: avoid to access NULL pointer when write metadata in xattr In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Chao Yu commit 35425ea2492175fd39f6116481fe98b2b3ddd4ca upstream. Christopher Head 2014-06-28 05:26:20 UTC described: "I tried to reproduce this on 3.12.21. Instead, when I do "echo hello > foo" in an ecryptfs mount with ecryptfs_xattr specified, I get a kernel crash: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] fsstack_copy_attr_all+0x2/0x61 PGD d7840067 PUD b2c3c067 PMD 0 Oops: 0002 [#1] SMP Modules linked in: nvidia(PO) CPU: 3 PID: 3566 Comm: bash Tainted: P O 3.12.21-gentoo-r1 #2 Hardware name: ASUSTek Computer Inc. G60JX/G60JX, BIOS 206 03/15/2010 task: ffff8801948944c0 ti: ffff8800bad70000 task.ti: ffff8800bad70000 RIP: 0010:[] [] fsstack_copy_attr_all+0x2/0x61 RSP: 0018:ffff8800bad71c10 EFLAGS: 00010246 RAX: 00000000000181a4 RBX: ffff880198648480 RCX: 0000000000000000 RDX: 0000000000000004 RSI: ffff880172010450 RDI: 0000000000000000 RBP: ffff880198490e40 R08: 0000000000000000 R09: 0000000000000000 R10: ffff880172010450 R11: ffffea0002c51e80 R12: 0000000000002000 R13: 000000000000001a R14: 0000000000000000 R15: ffff880198490e40 FS: 00007ff224caa700(0000) GS:ffff88019fcc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000bb07f000 CR4: 00000000000007e0 Stack: ffffffff811826e8 ffff8800a39d8000 0000000000000000 000000000000001a ffff8800a01d0000 ffff8800a39d8000 ffffffff81185fd5 ffffffff81082c2c 00000001a39d8000 53d0abbc98490e40 0000000000000037 ffff8800a39d8220 Call Trace: [] ? ecryptfs_setxattr+0x40/0x52 [] ? ecryptfs_write_metadata+0x1b3/0x223 [] ? should_resched+0x5/0x23 [] ? ecryptfs_initialize_file+0xaf/0xd4 [] ? ecryptfs_create+0xf4/0x142 [] ? vfs_create+0x48/0x71 [] ? do_last.isra.68+0x559/0x952 [] ? link_path_walk+0xbd/0x458 [] ? path_openat+0x224/0x472 [] ? do_filp_open+0x2b/0x6f [] ? __alloc_fd+0xd6/0xe7 [] ? do_sys_open+0x65/0xe9 [] ? system_call_fastpath+0x16/0x1b RIP [] fsstack_copy_attr_all+0x2/0x61 RSP CR2: 0000000000000000 ---[ end trace df9dba5f1ddb8565 ]---" If we create a file when we mount with ecryptfs_xattr_metadata option, we will encounter a crash in this path: ->ecryptfs_create ->ecryptfs_initialize_file ->ecryptfs_write_metadata ->ecryptfs_write_metadata_to_xattr ->ecryptfs_setxattr ->fsstack_copy_attr_all It's because our dentry->d_inode used in fsstack_copy_attr_all is NULL, and it will be initialized when ecryptfs_initialize_file finish. So we should skip copying attr from lower inode when the value of ->d_inode is invalid. Signed-off-by: Chao Yu Signed-off-by: Tyler Hicks Signed-off-by: Ben Hutchings --- fs/ecryptfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -1112,7 +1112,7 @@ ecryptfs_setxattr(struct dentry *dentry, } rc = vfs_setxattr(lower_dentry, name, value, size, flags); - if (!rc) + if (!rc && dentry->d_inode) fsstack_copy_attr_all(dentry->d_inode, lower_dentry->d_inode); out: return rc; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/