linux-ext4 - Re: [PATCH] ext4: don't read blocks from disk after extents being swapped in move_extent_per

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160212062158.GH11298@thunk.org>
Date:	Fri, 12 Feb 2016 01:21:58 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Eryu Guan <guaneryu@...il.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: don't read blocks from disk after extents being
 swapped in move_extent_per_page()

On Wed, Feb 10, 2016 at 11:16:45PM +0800, Eryu Guan wrote:
> I notice ext4/307 fails occasionally on ppc64 host, reporting md5
> checksum mismatch after moving data from original file to donor file.
> 
> The reason is that move_extent_per_page() calls __block_write_begin()
> and block_commit_write() to write saved data from original inode blocks
> to donor inode blocks, but __block_write_begin() not only maps buffer
> heads but also reads block content from disk if the size is not block
> size aligned. At this time the physical block number in mapped buffer
> head is pointing to the donor file not the original file, and that
> results in reading wrong data to page, which get written to disk in
> following block_commit_write call.

Thanks, applied.

					- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html