[PATCH 0/2] Fixes for partition scan of corrupted AIX disk

[Mauricio Oliveira]

I will resend with the releases in the subject line; sorry.

On Wed, Aug 15, 2018 at 5:58 PM, Mauricio Faria de Oliveira <
mfo at canonical.com> 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.
>
> Mauricio Faria de Oliveira (2):
>   partitions/aix: fix usage of uninitialized lv_info and lvname
>     structures
>   partitions/aix: append null character to print data from disk
>
>  block/partitions/aix.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> --
> 2.17.1
>
>


-- 
Mauricio Faria de Oliveira
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