]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
pps: do not crash when failed to register
authorJiri Slaby <jslaby@suse.cz>
Wed, 20 Jul 2016 22:45:08 +0000 (15:45 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 23 Jul 2016 01:25:54 +0000 (10:25 +0900)
commit368301f2fe4b07e5fb71dba3cc566bc59eb6705f
tree570a9b7bc5583381d4414500ce615c9f17ce03f4
parent2d6a4d64812bb12dda53704943b61a7496d02098
pps: do not crash when failed to register

With this command sequence:

  modprobe plip
  modprobe pps_parport
  rmmod pps_parport

the partport_pps modules causes this crash:

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: parport_detach+0x1d/0x60 [pps_parport]
  Oops: 0000 [#1] SMP
  ...
  Call Trace:
    parport_unregister_driver+0x65/0xc0 [parport]
    SyS_delete_module+0x187/0x210

The sequence that builds up to this is:

 1) plip is loaded and takes the parport device for exclusive use:

    plip0: Parallel port at 0x378, using IRQ 7.

 2) pps_parport then fails to grab the device:

    pps_parport: parallel port PPS client
    parport0: cannot grant exclusive access for device pps_parport
    pps_parport: couldn't register with parport0

 3) rmmod of pps_parport is then killed because it tries to access
    pardev->name, but pardev (taken from port->cad) is NULL.

So add a check for NULL in the test there too.

Link: http://lkml.kernel.org/r/20160714115245.12651-1-jslaby@suse.cz
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/pps/clients/pps_parport.c