The patch titled
Subject: pps: do not crash when failed to register
has been added to the -mm tree. Its filename is
pps-do-not-crash-when-failed-to-register.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pps-do-not-crash-when-failed-to-register.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pps-do-not-crash-when-failed-to-register.patch
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------------------------------------------------------
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;
_
Patches currently in -mm which might be from jslaby@xxxxxxx are
pps-do-not-crash-when-failed-to-register.patch
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