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… failure (HDFFV-6386) When H5O__cache_deserialize() fails after continuation messages have already been accumulated into cont_msg_info->msgs (e.g. the v1 'v1_pfx_nmesgs < oh->nmesgs' check at H5Ocache.c:305), it returned NULL while leaving the caller's H5O_protect() with oh == NULL. The existing cleanup in H5O_protect() only frees cont_msg_info->msgs when oh != NULL, so the continuation-message array was leaked. Free cont_msg_info->msgs in H5O__cache_deserialize()'s own done block on error. H5FL_seq_free() returns NULL, so this is safe against a double-free with the caller's guarded free. Found by OSS-Fuzz via the matio project's fuzzer (see HDFGroup#6386).
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Summary
Fixes a memory leak reported by OSS-Fuzz via the matio project's fuzzer (closes #6386).
\
Direct leak of 56 byte(s) ... allocated from:
# 3 H5O__add_cont_msg hdf5/src/H5Ocache.c
# 4 H5O__chunk_deserialize hdf5/src/H5Ocache.c
# 5 H5O__cache_deserialize hdf5/src/H5Ocache.c
...
# 17 H5Rdereference2
\\
Root cause
\H5O__cache_deserialize()\ allocates the continuation-message array
(\cont_msg_info->msgs, via \H5O__add_cont_msg()\ -> \H5FL_SEQ_REALLOC) while parsing the first object-header chunk. The caller \H5O_protect()\ only frees that array on the success path (H5Ocache.c:1075) or on failure *when \oh != NULL* (rule at H5Ocache.c:1142). When the deserialize fails after continuation messages were accumulated (e.g. the v1 \�1_pfx_nmesgs < oh->nmesgs\ check at H5Ocache.c:305), \H5O__cache_deserialize()\ returns \NULL\ and \H5O_protect()'s \oh\ stays \NULL, so its cleanup is skipped and the 56-byte array leaks.
Fix
Free \cont_msg_info->msgs\ in \H5O__cache_deserialize()'s own \done\ block on error. \H5FL_seq_free()\ returns \NULL, so this is safe against a double-free with the caller's guarded free (which becomes a no-op once the array is \NULL).
Verification
Compiles cleanly in both Release and Debug \hdf5-static\ builds and links into a Debug repro exercising matio's exact API paths (\H5Oget_info_by_name3\ + \H5Rdereference2\ on reference datasets). The leak is specific to v1 object headers (the post-continuation \�1_pfx_nmesgs < oh->nmesgs\ check), which is why the leak manifests in the 2.2.0 OSS-Fuzz environment described in the issue.
Checklist