Re: Issue 62071 in oss-fuzz: elfutils:fuzz-libdwfl: Null-dereference READ in chunk_compare

[Mark Wielaard <mark@klomp.org>]

Hi Evgeny,

Do you happen to know what clusterfuzz is trying to tell us? The
detailed report and reproducer testcase are not accessible (they
seems to require a google or github account to login).

It looks like somehow a NULL key got into the search tree. But I cannot
figure out how that would happen.

Thanks,

Mark

On Tue, 2023-09-05 at 22:01 -0700, ClusterFuzz-External via monorail
via Elfutils-devel wrote:
> Status: New
> Owner: ----
> CC: elfut...@sourceware.org, da...@adalogics.com, evv...@gmail.com, izzeem@google.com 
> Labels: ClusterFuzz Stability-Memory-AddressSanitizer Unreproducible Engine-libfuzzer OS-Linux Proj-elfutils Reported-2023-09-06
> Type: Bug
> 
> New issue 62071 by ClusterFuzz-External: elfutils:fuzz-libdwfl: Null-dereference READ in chunk_compare
> https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=62071
> 
> Detailed Report: https://oss-fuzz.com/testcase?key=5999675550072832
> 
> Project: elfutils
> Fuzzing Engine: libFuzzer
> Fuzz Target: fuzz-libdwfl
> Job Type: libfuzzer_asan_i386_elfutils
> Platform Id: linux
> 
> Crash Type: Null-dereference READ
> Crash Address: 0x000000a0
> Crash State:
>   chunk_compare
>   __tsearch
>   elf_getdata_rawchunk
>   
> Sanitizer: address (ASAN)
> 
> Crash Revision: https://oss-fuzz.com/revisions?job=libfuzzer_asan_i386_elfutils&revision=202308240000
> 
> Reproducer Testcase: https://oss-fuzz.com/download?testcase_id=5999675550072832
> 
> Issue filed automatically.
> 
> See https://google.github.io/oss-fuzz/advanced-topics/reproducing for instructions to reproduce this bug locally.
> 
> ************************* UNREPRODUCIBLE *************************
> 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.
> 
> It may be possible to reproduce by trying the following options:
> - Run testcase multiple times for a longer duration.
> - Run fuzzing without testcase argument to hit the same crash signature.
> 
> If it still does not reproduce, try a speculative fix based on the crash stacktrace and verify if it works by looking at the crash statistics in the report. We will auto-close the bug if the crash is not seen for 14 days.
> ******************************************************************
> When you fix this bug, please
>   * mention the fix revision(s).
>   * state whether the bug was a short-lived regression or an old bug in any stable releases.
>   * add any other useful information.
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> 
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