Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Mon, 14 Nov 2016 00:14:20 +0000 | Subject | [PATCH 3.16 108/346] pps: do not crash when failed to register |
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3.16.39-rc1 review patch. If anyone has any objections, please let me know.
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From: Jiri Slaby <jslaby@suse.cz>
commit 368301f2fe4b07e5fb71dba3cc566bc59eb6705f upstream.
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/pps/clients/pps_parport.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/pps/clients/pps_parport.c +++ b/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;
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