From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-560692-1519836133-2-1747756003010229497 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='uk', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1519836133; b=H8yEZVzWh0T8+kwO5fuBSKYNb9mzbFEkFf61QyaPqW2O6Of aXtRc7BQImsrx3jA8geC6NjkVRvJijseh4cr3qOkpYz9f6Zh/HyIfDoqIvHkkvI3 I1iRFAp6Of+9BH8ATWf4vNqw8IdLWIJ2vunFDXCjb+MRdC/eI3dfq1iIJvdRAJPc FTwNr/0lGucTaYAWMYpW5D7F+MMdPKh+4rQIgpO64H9F+baJdxoRBWq5IMdB8ow/ gKYC0X7jAEklyDLmqVmOfIqNvhcyxeGhSiH1KAvhbMJIQkUa9Q7NQ35Mdc0pAn69 5DgQsJiViNKAu4rxWhd5H/1o4nQeWXmPxeAGS7A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1519836133; bh=CMu/mbPftMh6iDunF5V 4u4XbKOch2lKbjkkFsSbEuHY=; b=xCPeqIwY8q9K+ohco5cTp8XgVPFYtnYNtkG ICsy/1pRAAJeGYp9+IWDUTh308oCmnLDl4B6q2T4+lc0HhAff8zQYaVrONEJK8Bq LuIFTHSHjISNYVKKhYyVIGZPdg3CElj5pwsubh71kgQiL9mpkVuP9A5Q8tPk0Rwr L7UaJ/NTSKbKs43hEve2lHzLldspBiuEYJzaQgrKxRDcIGgsu00R7l8iTAtGlBTl HDklkgYCh6ZAY9+qbJ9qJPeKC4z15qhgCLILFcuj5MCMBD03athBCWzlpvZjFv8b LMhicJFpIVjzT5rRHqwtWyQx9hfAAyrIPi72MXJ+MpUZFjikWSQ== ARC-Authentication-Results: i=1; mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752412AbeB1Qly (ORCPT ); Wed, 28 Feb 2018 11:41:54 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34764 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932754AbeB1QDY (ORCPT ); Wed, 28 Feb 2018 11:03:24 -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, "Abdul Haleem" , "Chandan Rajendra" Date: Wed, 28 Feb 2018 15:20:21 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 042/140] ext4: fix crash when a directory's i_size is too small In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.2.100-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Chandan Rajendra commit 9d5afec6b8bd46d6ed821aa1579634437f58ef1f upstream. On a ppc64 machine, when mounting a fuzzed ext2 image (generated by fsfuzzer) the following call trace is seen, VFS: brelse: Trying to free free buffer WARNING: CPU: 1 PID: 6913 at /root/repos/linux/fs/buffer.c:1165 .__brelse.part.6+0x24/0x40 .__brelse.part.6+0x20/0x40 (unreliable) .ext4_find_entry+0x384/0x4f0 .ext4_lookup+0x84/0x250 .lookup_slow+0xdc/0x230 .walk_component+0x268/0x400 .path_lookupat+0xec/0x2d0 .filename_lookup+0x9c/0x1d0 .vfs_statx+0x98/0x140 .SyS_newfstatat+0x48/0x80 system_call+0x58/0x6c This happens because the directory that ext4_find_entry() looks up has inode->i_size that is less than the block size of the filesystem. This causes 'nblocks' to have a value of zero. ext4_bread_batch() ends up not reading any of the directory file's blocks. This renders the entries in bh_use[] array to continue to have garbage data. buffer_uptodate() on bh_use[0] can then return a zero value upon which brelse() function is invoked. This commit fixes the bug by returning -ENOENT when the directory file has no associated blocks. Reported-by: Abdul Haleem Signed-off-by: Chandan Rajendra Signed-off-by: Ben Hutchings --- fs/ext4/namei.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -892,6 +892,10 @@ static struct buffer_head * ext4_find_en "falling back\n")); } nblocks = dir->i_size >> EXT4_BLOCK_SIZE_BITS(sb); + if (!nblocks) { + ret = NULL; + goto cleanup_and_exit; + } start = EXT4_I(dir)->i_dir_start_lookup; if (start >= nblocks) start = 0;