Bug#785672: Critical ext4 data corruption bug

[Elmar Stellnberger <estellnb@gmail.com>]

Am 19.05.15 um 01:12 schrieb Josh Triplett:
> Package: src:linux
> Version: 4.0.2-1
> Severity: critical
> Tags: upstream
>
> 4.0.3 includes a fix for a critical ext4 bug that can result in major
> data loss.  I believe this is the bug I just hit on my server, resulting
> in massive filesystem corruption.  See upstream commit
> d2dc317d564a46dfc683978a2e5a4f91434e9711 ("ext4: fix data corruption
> caused by unwritten and delayed extents"), which has been added to
> stable kernels 4.0.3 as well as much older stable kernels.
>
> Please consider incorporating this patch into the Debian kernels as soon
> as possible, including into the Jessie kernel.

Some time ago I also had some massive data corruption problem with an 
ext4 partition
which may also have been caused by the same bug. The notable thing is 
that other ext4
installations have worked fine for a long while in spite of this bug. No 
fsck had helped;
had to reformat having lost all data on the partition.
We need to warn any existing ext4 user! The patch should be distributed 
as soon as
possible. My recommendation would be not to use ext4 or to convert to 
btrfs unless
a fix is available. Otherwise assert your backups!

Elmar
> - Josh Triplett
>
> -- Package-specific info:
> ** Version:
> Linux version 4.0.0-1-amd64 (debian-kernel@lists.debian.org) (gcc version 4.9.2 (Debian 4.9.2-16) ) #1 SMP Debian 4.0.2-1 (2015-05-11)
>
> ** Command line:
> BOOT_IMAGE=/vmlinuz-4.0.0-1-amd64 root=/dev/mapper/data-root ro quiet
>
> ** Not tainted
>
> -- System Information:
> Debian Release: stretch/sid
>    APT prefers unstable
>    APT policy: (500, 'unstable'), (1, 'experimental')
> Architecture: amd64 (x86_64)
>
> Kernel: Linux 4.0.0-1-amd64 (SMP w/4 CPU cores)
> Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> Init: systemd (via /run/systemd/system)
>
> Versions of packages linux-image-4.0.0-1-amd64 depends on:
> ii  debconf [debconf-2.0]                   1.5.56
> ii  initramfs-tools [linux-initramfs-tool]  0.120
> ii  kmod                                    20-1
> ii  linux-base                              3.5
> ii  module-init-tools                       20-1
>
> Versions of packages linux-image-4.0.0-1-amd64 recommends:
> ii  firmware-linux-free  3.3
> pn  irqbalance           <none>
>
> Versions of packages linux-image-4.0.0-1-amd64 suggests:
> pn  debian-kernel-handbook  <none>
> ii  grub-pc                 2.02~beta2-23
> pn  linux-doc-4.0           <none>
>
> Versions of packages linux-image-4.0.0-1-amd64 is related to:
> pn  firmware-atheros        <none>
> pn  firmware-bnx2           <none>
> pn  firmware-bnx2x          <none>
> pn  firmware-brcm80211      <none>
> pn  firmware-intelwimax     <none>
> pn  firmware-ipw2x00        <none>
> pn  firmware-ivtv           <none>
> ii  firmware-iwlwifi        0.43
> pn  firmware-libertas       <none>
> pn  firmware-linux          <none>
> pn  firmware-linux-nonfree  <none>
> pn  firmware-myricom        <none>
> pn  firmware-netxen         <none>
> pn  firmware-qlogic         <none>
> pn  firmware-ralink         <none>
> pn  firmware-realtek        <none>
> pn  xen-hypervisor          <none>
>
> -- debconf information:
>    linux-image-4.0.0-1-amd64/postinst/depmod-error-initrd-4.0.0-1-amd64: false
>    linux-image-4.0.0-1-amd64/prerm/removing-running-kernel-4.0.0-1-amd64: true
>    linux-image-4.0.0-1-amd64/postinst/mips-initrd-4.0.0-1-amd64: