This bug was initially created as a copy of Bug #2167803 I am copying this bug because: Description of problem: Issue reported by Ilya Leoshkevich from IBM The tests pass, but fuzzing finds something: ==290951==ERROR: AddressSanitizer: SEGV on unknown address 0x62d100000000 (pc 0x0000011806be bp 0x03ffffff5a70 sp 0x03ffffff5a70 T0) ==290951==The signal is caused by a UNKNOWN memory access. #0 0x11806be in fill_window /home/iii/zlib-fuzz/build/zlib/build- libfuzzer/deflate.c:1604:24 #1 0x119d31f in deflate_fast /home/iii/zlib-fuzz/build/zlib/build- libfuzzer/deflate.c:1902:13 #2 0x118e60f in deflate /home/iii/zlib-fuzz/build/zlib/build- libfuzzer/deflate.c:1066:18 #3 0x1174983 in Deflate /home/iii/zlib-fuzz/fuzz_target.cpp:250:13 #4 0x1174983 in RunDeflateOp /home/iii/zlib- fuzz/fuzz_target.cpp:795:15 #5 0x1174983 in ExecutePlan /home/iii/zlib- fuzz/fuzz_target.cpp:1006:5 #6 0x1174983 in LLVMFuzzerTestOneInput /home/iii/zlib- fuzz/fuzz_target.cpp:1075:3 Ilya also found a fix for this issue that has been committed by upstream author: https://github.com/madler/zlib/commit/2d80d3f6b52f9fa454c26c89d2d6a1790e1cecb0
MR: https://gitlab.com/redhat/centos-stream/rpms/zlib/-/merge_requests/27
Merged