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.

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

dsinclair: do you mind taking a look at this please?

rharrison@ can you ptal?

rharrison@, this is being tracked as a stable release blocker. Have you had a chance to take a look at this bug yet?

Sorry about missing this, I didn't notice it was marked as high priority.

This shouldn't be a release blocker, since this a XFA only fuzzer and XFA isn't enabled.

No longer reproduces on HEAD. This issues looks similar to other issues recently resolved in the resampling GIF code paths.

Likely fixed by https://pdfium-review.googlesource.com/14630

ClusterFuzz has detected this issue as fixed in range 503743:503814.

Detailed report: https://clusterfuzz.com/testcase?key=4965284925669376

Fuzzer: libFuzzer_pdf_codec_gif_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Heap-buffer-overflow READ 4
Crash Address: 0x6020000004b8
Crash State:
  CCodec_ProgressiveDecoder::ReSampleScanline
  CCodec_ProgressiveDecoder::GifReadScanline
  CGifContext::ReadScanline
  
Sanitizer: address (ASAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=400732:400874
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=503743:503814

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4965284925669376

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md 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 4965284925669376 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