From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F95DC2BA19 for ; Thu, 23 Apr 2020 07:27:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 545D720736 for ; Thu, 23 Apr 2020 07:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725863AbgDWH1h (ORCPT ); Thu, 23 Apr 2020 03:27:37 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:41145 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725562AbgDWH1g (ORCPT ); Thu, 23 Apr 2020 03:27:36 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0TwPIcx9_1587626854; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0TwPIcx9_1587626854) by smtp.aliyun-inc.com(127.0.0.1); Thu, 23 Apr 2020 15:27:34 +0800 From: Jeffle Xu To: tytso@mit.edu, jack@suse.cz Cc: linux-ext4@vger.kernel.org, joseph.qi@linux.alibaba.com Subject: [PATCH] ext4: fix error pointer dereference Date: Thu, 23 Apr 2020 15:27:34 +0800 Message-Id: <1587626854-73470-1-git-send-email-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Don't pass error pointers to brelse(). commit 7159a986b420 ("ext4: fix some error pointer dereferences") has fixed some cases, fix the remaining one case. Once ext4_xattr_block_find()->ext4_sb_bread() failed, error pointer is stored in @bs->bh, which will be passed to brelse() in the cleanup routine of ext4_xattr_set_handle(). This will then cause a NULL panic crash in __brelse(). BUG: unable to handle kernel NULL pointer dereference at 000000000000005b RIP: 0010:__brelse+0x1b/0x50 Call Trace: ext4_xattr_set_handle+0x163/0x5d0 ext4_xattr_set+0x95/0x110 __vfs_setxattr+0x6b/0x80 __vfs_setxattr_noperm+0x68/0x1b0 vfs_setxattr+0xa0/0xb0 setxattr+0x12c/0x1a0 path_setxattr+0x8d/0xc0 __x64_sys_setxattr+0x27/0x30 do_syscall_64+0x60/0x250 entry_SYSCALL_64_after_hwframe+0x49/0xbe In this case, @bs->bh stores '-EIO' actually. Fixes: fb265c9cb49e ("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases") Signed-off-by: Jeffle Xu Reviewed-by: Joseph Qi Cc: stable@kernel.org # 2.6.19 --- fs/ext4/xattr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 21df43a..c0ebd0f 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1800,8 +1800,10 @@ struct ext4_xattr_block_find { if (EXT4_I(inode)->i_file_acl) { /* The inode already has an extended attribute block. */ bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO); - if (IS_ERR(bs->bh)) + if (IS_ERR(bs->bh)) { + bs->bh = NULL; return PTR_ERR(bs->bh); + } ea_bdebug(bs->bh, "b_count=%d, refcount=%d", atomic_read(&(bs->bh->b_count)), le32_to_cpu(BHDR(bs->bh)->h_refcount)); -- 1.8.3.1