diff options
authorJiri Slaby <>2016-07-20 15:45:08 -0700
committerLinus Torvalds <>2016-07-23 10:25:54 +0900
commit368301f2fe4b07e5fb71dba3cc566bc59eb6705f (patch)
parent2d6a4d64812bb12dda53704943b61a7496d02098 (diff)
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: Signed-off-by: Jiri Slaby <> Acked-by: Rodolfo Giometti <> Cc: <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c
index 38a8bbe..83797d8 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 */