From: Jiri Slaby <jslaby@xxxxxxx> Subject: 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: [<ffffffffa110301d>] parport_detach+0x1d/0x60 [pps_parport] Oops: 0000 [#1] SMP ... Call Trace: [<ffffffffa036a185>] parport_unregister_driver+0x65/0xc0 [parport] [<ffffffff810ff667>] SyS_delete_module+0x187/0x210 === 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@xxxxxxx Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> Acked-by: Rodolfo Giometti <giometti@xxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/pps/clients/pps_parport.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN drivers/pps/clients/pps_parport.c~pps-do-not-crash-when-failed-to-register drivers/pps/clients/pps_parport.c --- a/drivers/pps/clients/pps_parport.c~pps-do-not-crash-when-failed-to-register +++ a/drivers/pps/clients/pps_parport.c @@ -195,7 +195,7 @@ static void parport_detach(struct parpor 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
