ACK / APPLIED[C/Unstable]: [Cosmic][SRU Bionic/Xenial/Trusty][PATCH 0/2] Fixes for partition scan of corrupted AIX disk

[Seth Forshee]

On Tue, Aug 21, 2018 at 11:01:51AM -0300, Mauricio Faria de Oliveira wrote:
> BugLink: https://bugs.launchpad.net/bugs/1787281
> 
> [Impact]
> 
>  * Users with disks/LUNs used for AIX operating system installations
>    previously, which possibly undergone overwrites/corruption on the
>    partition table, might hit kernel failures during partition scan
>    of such disk/LUN, and possibly hang the system (seen with retries).
> 
>  * The Linux kernel should be robust to corrupted disk data, performing
>    a better sanitization/checks and not failing.
> 
>  * The fix are a couple of simple logic changes to make the code
>    of the AIX partition table parser more robust.
> 
> [Test Case]
> 
>  * Run the partition scan on the (trimmed) disk image of the AIX lun.
>    (It's not provided here since it contains customer data), with this
>    command:
> 
>    $ sudo losetup --find --show --partscan rlv_grkgld.1mb
> 
>  * On failure, the command hangs, and messages like these are printed
>    to the console, depending on the kernel version (see tests below)
> 
>    [ 270.506420] partition (null) (3 pp's found) is not contiguous
> 
>    [ 270.597428] BUG: unable to handle kernel paging request at 0000000000001000
>    [ 270.599525] IP: [<ffffffff81379d4d>] strnlen+0xd/0x40
> 
>  * On success, the command prints a loop device name, for example:
> 
>    /dev/loop0
> 
> [Regression Potential]
> 
>  * Low. Both changes are simple improvements in logic.
> 
>  * This affects users which mount disks/LUNs from the AIX OS;
>    it should only change behavior for users which relied on a
>    uninitialized variables to work correctly during partition
>    scan of those disks/LUNs which should be rare as the code
>    is likely to fail as we observe in this scenario.
> 
>  * This has been tested on Cosmic, Bionic, Xenial, and Trusty.

Acked-by: Seth Forshee <seth.forshee at canonical.com>

Applied to cosmic/master-next and unstable/master, thanks!