This is a serious security regression. If you are not able to fix this quickly, please revert the change that introduced it.

If this doesn't affect a release branch, or has not been properly classified for severity, please update the Security_Impact or Security_Severity labels, and remove the ReleaseBlock label. To disable this altogether, apply ReleaseBlock-NA.

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Over to one of the OWNERS, can you PTAL?

"Enable display zoom slider by default" is possibly relevant.

A UAF in ui::Layer::OnDeviceScaleFactorChanged on line 948 is:

const float old_device_scale_factor = device_scale_factor_;

So it's being called on a Layer that was deleted. Something appears to be holding ui::Layers incorrectly then.

I am unable to repro this failure locally using clusterfuzz repro steps.

It seems to be caused when a zoom in/out is triggered via a keyboard shortcut and a layer that has been deleted is accessed to update the new device scale factor.

Any ideas on what might be causing this or attempts at repro?

ClusterFuzz has detected this issue as fixed in range 552562:552565.

Detailed report: https://clusterfuzz.com/testcase?key=5899615690555392

Fuzzer: inferno_webbot
Job Type: linux_asan_chrome_chromeos
Platform Id: linux

Crash Type: Heap-use-after-free READ 4
Crash Address: 0x616000194ef8
Crash State:
  ui::Layer::OnDeviceScaleFactorChanged
  ui::Layer::OnDeviceScaleFactorChanged
  ui::Layer::OnDeviceScaleFactorChanged
  
Sanitizer: address (ASAN)

Recommended Security Severity: High

Regressed: https://clusterfuzz.com/revisions?job=linux_asan_chrome_chromeos&range=552206:552209
Fixed: https://clusterfuzz.com/revisions?job=linux_asan_chrome_chromeos&range=552562:552565

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5899615690555392

Additional requirements: Requires Gestures

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

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 5899615690555392 is verified as fixed, so closing issue as verified.

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

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot