From: Jiri Slaby <jslaby@suse.cz>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, Jiri Slaby <jslaby@suse.cz>,
Rodolfo Giometti <giometti@enneenne.com>
Subject: [PATCH -resend] pps: do not crash when failed to register
Date: Thu, 14 Jul 2016 13:52:45 +0200 [thread overview]
Message-ID: <20160714115245.12651-1-jslaby@suse.cz> (raw)
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.
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
next reply other threads:[~2016-07-14 11:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 11:52 Jiri Slaby [this message]
2016-07-14 12:05 ` [PATCH -resend] pps: do not crash when failed to register Rodolfo Giometti
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