| Summary: | [Patch] Linux mutex leak in drm_dp_get_mst_branch | ||||||
|---|---|---|---|---|---|---|---|
| Product: | DRI | Reporter: | Adam J. Richter <adam_richter2004> | ||||
| Component: | General | Assignee: | Default DRI bug account <dri-devel> | ||||
| Status: | RESOLVED FIXED | QA Contact: | |||||
| Severity: | normal | ||||||
| Priority: | medium | ||||||
| Version: | unspecified | ||||||
| Hardware: | x86-64 (AMD64) | ||||||
| OS: | Linux (All) | ||||||
| Whiteboard: | |||||||
| i915 platform: | i915 features: | ||||||
| Attachments: |
|
||||||
Created attachment 118904 [details] [review] Patch to fix mutex leak on error return of drm_dp_get_mst_branch_device in linux-4.3-rc5/drivers/gpu/drm/drm_dp_mst_topology.c Please send your (In reply to Adam J. Richter from comment #0) > Anyhow, if the patch looks good, I would be delighted to if the appropriate > person (Dave?) would integrate it for submission upstream. Good catch! Reviewed-by: Jani Nikula <jani.nikula@intel.com> Please send the patch in proper patch format with your Signed-off-by to dri-devel@lists.freedesktop.org mailing list. See Documentation/SubmittingPatches for help. commit 6749c9f023d49adca3ca4773e93282b95ceebfb5 Author: Adam Richter <adamrichter4@gmail.com> Date: Fri Oct 16 03:33:02 2015 -0700 drm: fix mutex leak in drm_dp_get_mst_branch_device also cherry-picked to v4.3 as commit 30730c7f5943b3beace1e29f7f1476e05de3da14 Author: Adam Richter <adamrichter4@gmail.com> Date: Fri Oct 16 03:33:02 2015 -0700 drm: fix mutex leak in drm_dp_get_mst_branch_device |
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.
I believe I have found a mutex leak in drm_dp_get_mst_branch_device() in linux/drivers/gpu/drm/drm_dp_mst_topology.c in kernels 4.2-rc1 through the current version, 4.3-rc5, where the function can take an error exit without doing mutex_unlock(&mgr_lock). I have attached a proposed patch. Unfortunately, since I made the patch, I have not been able to trigger the error branch that the patch fixes, but I did find the bug by observing that error branch executing and printing an error message that I believe is unique to that branch ("*ERROR* failed to lookup MSTB"): [ 36.944273] [drm:gen8_irq_handler [i915]] *ERROR* The master control interrupt lied (SDE)! [ 74.576811] [drm:drm_dp_get_mst_branch_device [drm_kms_helper]] *ERROR* failed to lookup MSTB with lct 2, rad 10 [ 74.587704] BUG: workqueue leaked lock or atomic: kworker/u8:0/0x00000000/6 [ 74.587704] last function: i915_digport_work_func [i915] [ 74.655752] [drm:gen8_irq_handler [i915]] *ERROR* The master control interrupt lied (SDE)! I think this patch is also arguably an infinitesimal improvement in that it depends less on the optimizer, by reducing two references to port->mstb to one. Anyhow, if the patch looks good, I would be delighted to if the appropriate person (Dave?) would integrate it for submission upstream. Thanks in advance for any feedback on this.