Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753104AbZCKGNL (ORCPT ); Wed, 11 Mar 2009 02:13:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751539AbZCKGM5 (ORCPT ); Wed, 11 Mar 2009 02:12:57 -0400 Received: from anchor-post-2.mail.demon.net ([195.173.77.133]:52149 "EHLO anchor-post-2.mail.demon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495AbZCKGM5 (ORCPT ); Wed, 11 Mar 2009 02:12:57 -0400 Message-ID: <49B75666.5030106@lougher.demon.co.uk> Date: Wed, 11 Mar 2009 06:12:54 +0000 From: Phillip Lougher User-Agent: Thunderbird 2.0.0.18 (X11/20081125) MIME-Version: 1.0 To: Phillip Lougher CC: Geert Uytterhoeven , Stefan Lippers-Hollmann , Linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [GIT PULL] Squashfs fixes for 2.6.29? References: <49AF30EC.8010205@lougher.demon.co.uk> <200903092239.13078.s.L-H@gmx.de> <49B5CCB7.5030404@lougher.demon.co.uk> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3853 Lines: 110 Phillip Lougher wrote: > Geert Uytterhoeven wrote: >> On Tue, 10 Mar 2009, Phillip Lougher wrote: >>> Stefan Lippers-Hollmann wrote: >>>> This patch seems to break squashfs for me on i386 and amd64. >>>> Test environment is a squashed filesystem image (live CD image, but also >>>> tested manually with a loop mounted iso9660 and loop mounted squashfs; >>>> kernel 2.6.29-rc7-git2). The squashfs image has been created with >>>> squashfs-tools CVS[1] as of today (latest commit 2009-03-03). >>>> >>> Can you send me a filesystem (or link to one) which exhibits this? Zlib is >>> obviously showing unexpected behaviour... >> I see the same thing here. I'll send you a test file system by private email. >> > > OK thanks, I've received it, and reproduced the problem :-) > >> The patch below fixes it. It seems zlib sometimes does need an additional >> loop ;-) >> > > Yes thanks. > >> Note that I expect it may now loop forever in case of file system corruption. > > This is the next thing, to redo the file system corruption patch. > Hi, The following patch fixes the problems you've experienced with your test filesystems (thanks for making them available), and also deals with the corrupted filesystems issue. It correctly works with all the corrupted filesystems sent earlier this year. The problem arises due to an unexpected corner-case with zlib which the corrupted filesystems patch didn't address. Very occasionally zlib exits needing a couple of extra bytes of input (1 and 2 bytes in the test filesystems), but with avail_out == 0 and no more output buffers available. This situation was incorrectly flagged as an error by the corrupted filesystems patch. I unfortunately didn't anticipate this scenario because it seems contrary to expectation that zlib will be still reading input having produced all the expected output. The fix is to not print an error if zlib wants more input bytes and there's more input bytes to be read. Geert I can put a signed off line from you on the patch if you like (as you sent the original fix). I could add reported and tested lines from both of you? They seem to be being used more often and sound a good idea. Thanks Phillip diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c index 321728f..b85173f 100644 --- a/fs/squashfs/block.c +++ b/fs/squashfs/block.c @@ -166,6 +166,22 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index, bytes = length; do { + if (msblk->stream.avail_out == 0) { + if (page < pages) { + msblk->stream.next_out = buffer[page++]; + msblk->stream.avail_out = + PAGE_CACHE_SIZE; + } else if (msblk->stream.avail_in > 0 + || bytes == 0) { + ERROR("zlib_inflate tried to " + "decompress too much data, " + "expected %d bytes. Zlib " + "data probably corrupt\n", + srclength); + goto release_mutex; + } + } + if (msblk->stream.avail_in == 0 && k < b) { avail = min(bytes, msblk->devblksize - offset); bytes -= avail; @@ -184,19 +200,6 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index, offset = 0; } - if (msblk->stream.avail_out == 0) { - if (page == pages) { - ERROR("zlib_inflate tried to " - "decompress too much data, " - "expected %d bytes. Zlib " - "data probably corrupt\n", - srclength); - goto release_mutex; - } - msblk->stream.next_out = buffer[page++]; - msblk->stream.avail_out = PAGE_CACHE_SIZE; - } - if (!zlib_init) { zlib_err = zlib_inflateInit(&msblk->stream); if (zlib_err != Z_OK) { -- 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/