[Bug 1979342] Re: ata_id command provides wrong information for ATA devices

[Dan Streetman]

Unfortunately, while the udev info for affected ATA drives might be
'wrong', that udev info is what all existing Bionic users are currently
using, and expecting. Backporting this patch would change the udev info
for all Bionic users (with affected ATA drives) which very likely would
cause regressions or at least unexpected behavior.

I think the existing behavior of udev in Bionic needs to remain
unchanged, and this patch should not be backported.

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https://bugs.launchpad.net/bugs/1979342

Title:
  ata_id command provides wrong information for ATA devices

Status in systemd package in Ubuntu:
  New
Status in systemd source package in Bionic:
  Confirmed

Bug description:
  [DESCRIPTION]

  Original revisions of the SAT (SCSI-ATA Translation) specification
  required that all sense data be reported in Descriptor Format (72h).
  Later revisions specifcally allow and account for sense data being
  reported in Fixed Format (70h).
  The current code checks for a Descriptor Format sense structure (0x72),
  then looks specifically at the first byte of the first descriptor for the
  ATA specific code 0x9, cross referencing it with the first byte which is
  just a length field 0x0c (as a sanity check).

  The code did not account for the Fixed Format case (0x70).
  Upstream commit 402fecff19d42("ata_id: Add check for fixed format sense codes (#13654)")
  fixed this by checking for the Fixed Format case(0x70) adn then falling back to 
  using the top-level SCSI Sense data for the Additional Sense code (0x0) and 
  then the Additional Sense Code Qualifier (0x1d).

  [TEST CASE]

  To test this you need and ATA device.

  Without the patch id_ata command returns error code 2.

  With the patch it returns the correct information :

  root at machine:~# ./ata_id /dev/sdn -x
  ID_ATA=1
  ID_TYPE=disk
  ID_BUS=ata
  ID_MODEL=HGST_HUH728080ALE604
  ID_MODEL_ENC=HGST\x20HUH728080ALE604\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
  ID_REVISION=A4GNW7J0
  ID_SERIAL=HGST_HUH728080ALE604_ZZZZH3VX
  ID_SERIAL_SHORT=ZZZZH3VX
  ...

  (see commit message for more details)

  
  [REGRESSION POTENTIAL]

  This commit changes disk_identify_command() function in src/udev/ata_id/ata_id.c
  and therefore any regression potential will affect only this executable (and any other
  that may use it).

  
  [OTHER]

  The fix is already in Focal.
  Currently only Bionic is affected.

  Upstream fix : 
  https://github.com/systemd/systemd/commit/402fecff19d42bb06caed1a3a32262c18087b7f1

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