Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH -resend] pps: do not crash when failed to register | Date | Thu, 14 Jul 2016 13:52:45 +0200 |
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With this command sequence: modprobe plip modprobe pps_parport rmmod pps_parport the partport_pps modules causes this crash:
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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
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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.
Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Rodolfo Giometti <giometti@enneenne.com> --- drivers/pps/clients/pps_parport.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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; -- 2.9.1
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