re: media: rcar-vin: add group allocator functions

From: Colin Ian King
Date: Tue Apr 24 2018 - 09:14:26 EST


Hi there,

While running static analysis on linux-next today a null pointer
dereference issue was detected by CoverityScan. The following commit
introduced the issue:

commit 3bb4c3bc85bf77a76c921671800bde2e1bf82a88
Author: Niklas SÃderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
Date: Sat Apr 14 07:57:18 2018 -0400

media: rcar-vin: add group allocator functions

The analysis is as follows:

339 static void rvin_group_put(struct rvin_dev *vin)
340 {
341 mutex_lock(&vin->group->lock);
342
1. assign_zero: Assigning: vin->group = NULL.

343 vin->group = NULL;
344 vin->v4l2_dev.mdev = NULL;
345
CID 1468359 (#1 of 1): Explicit null dereferenced (FORWARD_NULL)
2. var_deref_op: Dereferencing null pointer vin->group.

346 if (WARN_ON(vin->group->vin[vin->id] != vin))
347 goto out;
348

vin->group is NULL however the WARN_ON is dereferencing it, causing an
OOPS. I don't know how this should be fixed, hence I am sending this
bug report.

Regards,

Colin