Avoid UB in LRUHandle key storage#1327
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Store cache entry keys in tail storage after LRUHandle instead of using a one-byte trailing array. Treating key_data[1] as variable-length storage and copying keys longer than one byte into it writes past the declared array subobject, which is undefined behavior in C++. Add a cache test covering insertion, lookup, and deletion of a key longer than one byte.
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Potentially addresses #1325.
Fixes C++ undefined behavior in the LRU cache entry key storage.
LRUHandleusedchar key_data[1]as variable-length trailing storage and copied arbitrary-length keys into it(In cache.cc). For keys longer than one byte, this writes past the declared array subobject even though it remains within the malloc allocation.This patch stores keys in tail storage after
LRUHandleinstead, preserving the single-allocation layout.I do not have access to the custom HWASan runtime from the issue report, so I cannot directly verify the original sanitizer failure. The change removes the fixed trailing array pattern identified in the report and adds a cache test for keys longer than one byte.
Tested:
clang-format -i --style=file util/cache.cc util/cache_test.ccbuild/tools-venv/bin/ctest --test-dir build/cmake --output-on-failure