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Issue 781618 link

Starred by 2 users

Issue metadata

Status: WontFix
Owner:
Closed: Jul 19
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux
Pri: 2
Type: Bug



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Data race in webrtc::XErrorTrap::XErrorTrap

Project Member Reported by ClusterFuzz, Nov 5 2017

Issue description

Detailed report: https://clusterfuzz.com/testcase?key=6702841405374464

Fuzzer: phoglund_webrtc_peerconnection
Job Type: linux_tsan_chrome_mp
Platform Id: linux

Crash Type: Data race WRITE 4
Crash Address: 0x7f327b59b8f8
Crash State:
  webrtc::XErrorTrap::XErrorTrap
  webrtc::MouseCursorMonitorX11::Capture
  webrtc::DesktopAndCursorComposer::CaptureFrame
  
Sanitizer: thread (TSAN)

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6702841405374464

Additional requirements: Requires HTTP

Issue filed automatically.

See https://github.com/google/clusterfuzz-tools for more information.

Note: This crash might not be reproducible with the provided testcase. That said, for the past 14 days we've been seeing this crash frequently. If you are unable to reproduce this, please try a speculative fix based on the crash stacktrace in the report. The fix can be verified by looking at the crash statistics in the report, a day after the fix is deployed. We will auto-close the bug if the crash is not seen for 14 days.
 
Cc: kkaluri@chromium.org
Components: Blink>WebRTC
Labels: M-64 Test-Predator-Wrong CF-NeedsTriage
Unable to provide possible suspect using Predator, CL and Code Search.
Could someone please look into the issue.

Thank You.
Components: -Blink>WebRTC Internals>WebRTC Blink>GetUserMedia>Desktop
Owner: m...@chromium.org
miu@ can you help with triage?
Project Member

Comment 4 by ClusterFuzz, Nov 17 2017

Labels: ClusterFuzz-Top-Crash ReleaseBlock-Beta
Testcase 6702841405374464 is a top crash on ClusterFuzz for linux platform. Please prioritize fixing this crash.

Marking this crash as a Beta release blocker.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

Comment 5 by ajha@chromium.org, Nov 20 2017

Cc: zijiehe@chromium.org
Cc'ing zijiehe@ as well from  Issue 778035  for inputs on this.


This is marked as Beta blocker and M-64 will be branched in ~1 week time. If possible, please plan the fix before branch point.

Thank you!
This looks like a very old bug; I do not think this should be a release blocker.
(see the comment in the source code https://cs.chromium.org/chromium/src/third_party/webrtc/modules/desktop_capture/x11/x_error_trap.cc?rcl=2707fb2782e7a47d0f53cf8e561bef0bc00fad66&l=26)

The fix is straightforward: since X connection is single-threaded, adding thread_local to both g_xserver_error_trap_enabled and g_last_xserver_error_code is sufficient.

Comment 7 by m...@chromium.org, Nov 20 2017

Owner: zijiehe@chromium.org
Status: Assigned (was: Untriaged)


This is marked as Beta blocker for M-64 and would be good to have all the Beta blockers resolved before branch point. M-64 will be branched in few days.

zijiehe@,Could you please have a look and help in further investigation.
Thanks..!
Labels: -ReleaseBlock-Beta No-ReleaseBlock-Beta
I would remove release-blocker if you do not have other concern.
Cc: mbonadei@chromium.org phoglund@chromium.org
 Issue 788497  has been merged into this issue.
Owner: jamiewa...@chromium.org
Sorry for the late response.
thread_local is forbidden within Chromium because of the weird behavior on Mac OSX. Though this file is for Linux only, I do not want to break the rule. Except for the thread_local, I have not seen a very good solution. (base/threading/thread_local.h is not available in webrtc)

Since I am not working on Chrome anymore, investing more time on this long-term but tiny issue seems not worthy. Assign this bug back to Jamie.

I am happy to help on this issue, but cannot make critical decision anymore. So feel free to talk to me for the background or my proposal.
Project Member

Comment 12 by ClusterFuzz, Jul 19

Status: WontFix (was: Assigned)
ClusterFuzz testcase 6723242164486144 is flaky and no longer crashes, so closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

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