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drm: fix mutex leak in drm_dp_get_mst_branch_device 

In Linux 4.3-rc5, there is an error case in drm_dp_get_branch_device
that returns without releasing mgr->lock, resulting a spew of kernel
messages about a kernel work function possibly having leaked a mutex
and presumably more serious adverse consequences later.  This patch
changes the error to "goto out" to unlock the mutex before returning.

[airlied: grabbed from drm-next as it fixes something we've seen]

Signed-off-by: Adam J. Richter <adam_richter2004@yahoo.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Adam Richter 2015-10-16 03:33:02 -07:00 committed by Dave Airlie
parent 1099f86044
commit 30730c7f59
1 changed files with 4 additions and 3 deletions
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7
drivers/gpu/drm/drm_dp_mst_topology.c
View File

@ -1194,17 +1194,18 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
list_for_each_entry(port, &mstb->ports, next) { list_for_each_entry(port, &mstb->ports, next) {
if (port->port_num == port_num) { if (port->port_num == port_num) {
if (!port->mstb) { mstb = port->mstb;
if (!mstb) {
DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]); DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
return NULL; goto out;
} }
mstb = port->mstb;
break; break;
} }
} }
} }
kref_get(&mstb->kref); kref_get(&mstb->kref);
out:
mutex_unlock(&mgr->lock); mutex_unlock(&mgr->lock);
return mstb; return mstb;
} }