# DF-0267 -- Low

## Verdict: REPRODUCED (source-confirmed)

REAL: fixed_built is a plain int checked/set with no serialization; two concurrent first-callers to inflate_trees_fixed both init shared fixed_mem[530] via the shared 'f' huft counter -> corrupted fixed Huffman tables. Tiny window; DragonFly's serialized net stack mitigates.

## Impact ceiling
none

## Cited refs
- sys/net/zlib.c:4496
- sys/net/zlib.c:4531

## Fix
Mark fixed_built volatile + document that overlapped builds corrupt fixed_mem; full fix is to build fixed tables once at boot. Partial (compiles).

## Validation
Combined 60-finding fix kernel (findings/poc/_low_merged.patch) built `make -j6 nativekernel KERNCONF=X86_64_GENERIC` => rc=0, 0 errors, -Werror. fix_status=not_testable.