]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
drm/dp_mst: Check if primary mstb is null
authorStanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Fri, 9 Nov 2018 09:00:12 +0000 (11:00 +0200)
committerLyude Paul <lyude@redhat.com>
Fri, 9 Nov 2018 17:27:25 +0000 (12:27 -0500)
commit23d8003907d094f77cf959228e2248d6db819fa7
tree2a6e48e2f540a4127e182126d7a060e0988474c6
parentcf3d02a185edf449d30465dae8d22a4979545829
drm/dp_mst: Check if primary mstb is null

Unfortunately drm_dp_get_mst_branch_device which is called from both
drm_dp_mst_handle_down_rep and drm_dp_mst_handle_up_rep seem to rely
on that mgr->mst_primary is not NULL, which seem to be wrong as it can be
cleared with simultaneous mode set, if probing fails or in other case.
mgr->lock mutex doesn't protect against that as it might just get
assigned to NULL right before, not simultaneously.

There are currently bugs 107738, 108616 bugs which crash in
drm_dp_get_mst_branch_device, caused by this issue.

v2: Refactored the code, as it was nicely noticed.
    Fixed Bugzilla bug numbers(second was 108616, but not 108816)
    and added links.

[changed title and added stable cc]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Cc: stable@vger.kernel.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108616
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107738
Link: https://patchwork.freedesktop.org/patch/msgid/20181109090012.24438-1-stanislav.lisovskiy@intel.com
drivers/gpu/drm/drm_dp_mst_topology.c