dsinclair: can you please take a look? Though this might actually be bad behaviour in harfbuzz that pdfium is exposing.

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

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npm@ do you have time to look at some font stuff?

This is probably caused by freetype roll: 83b55ffcf303b35caaf048c76c9f9b89da2c3698

I think this is similar to  issue 758478  and would benefit from a fix in HarfBuzz.

Yeah, I can reproduce this and the issue appears to be that HarfBuzz in fb-ft.cc uses

static void
_hb_ft_font_destroy (hb_ft_font_t *ft_font)

and casts it to hb_destroy_func_t when setting the funcs. As a result, this later gets called as a hb_destroy_func_t, which is undefined behavior (C++14 5.2.10/6, since I was curious). I can't see 758478, so I can't really comment on that.

Note that this test case actually produces two of these sort of ubsan reports. The one in comment 9 is the first, the second is against a function in hb-face.cc

_hb_face_for_data_closure_destroy(hb_face_for_data_closure_t*)

which is also cast to hb_destroy_func_t (aka void *(void*)) and then later called as a hb_destroy_func_t.

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ClusterFuzz has detected this issue as fixed in range 513517:513548.

Detailed report: https://clusterfuzz.com/testcase?key=6020511204376576

Fuzzer: libFuzzer_pdfium_fuzzer
Job Type: libfuzzer_chrome_ubsan
Platform Id: linux

Crash Type: Incorrect-function-pointer-type
Crash Address: 
Crash State:
  hb_font_destroy
  af_face_globals_free
  destroy_face
  
Sanitizer: undefined (UBSAN)

Recommended Security Severity: Medium

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_ubsan&range=484588:484759
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_ubsan&range=513517:513548

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6020511204376576

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reference.md for more information.

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

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

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