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| author | Jiri Slaby <jslaby@suse.cz> | 2016-07-20 15:45:08 -0700 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2016-08-07 21:59:22 -0400 |
| commit | 9c5125ac23143c28f7b4cc1530a4dd06a83c086e (patch) | |
| tree | 252cbe76c8f99081ccb417f30016f8832cb3c7a3 | |
| parent | b863398c0f636e43fac9a9cb5b7632a0e05ef572 (diff) | |
| download | lwn-9c5125ac23143c28f7b4cc1530a4dd06a83c086e.tar.gz lwn-9c5125ac23143c28f7b4cc1530a4dd06a83c086e.zip | |
pps: do not crash when failed to register
[ Upstream commit 368301f2fe4b07e5fb71dba3cc566bc59eb6705f ]
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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
| -rw-r--r-- | drivers/pps/clients/pps_parport.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c index 38a8bbe74810..83797d89c30f 100644 --- a/drivers/pps/clients/pps_parport.c +++ b/drivers/pps/clients/pps_parport.c @@ -195,7 +195,7 @@ static void parport_detach(struct parport *port) struct pps_client_pp *device; /* FIXME: oooh, this is ugly! */ - if (strcmp(pardev->name, KBUILD_MODNAME)) + if (!pardev || strcmp(pardev->name, KBUILD_MODNAME)) /* not our port */ return; |