Fix unsigned wrap in bzdecompress() output realloc at source_len UINT_MAX#22432
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…_MAX The input guard rejects only source_len > UINT_MAX, so source_len == UINT_MAX is permitted and assigned to bzs.avail_out (unsigned int). The per-iteration realloc then computed bzs.avail_out+1 in unsigned int arithmetic, which wraps to 0 at UINT_MAX, allocating no headroom while bz2 still believes avail_out bytes are available at next_out: the next decompress round writes past the buffer. Compute the term as (size_t)bzs.avail_out + 1 so the increment is done in size_t and cannot wrap, matching the (size_t) casts already used on the same call.
Girgias
approved these changes
Jun 25, 2026
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The input guard rejects only source_len > UINT_MAX, so source_len == UINT_MAX is permitted and assigned to bzs.avail_out (unsigned int). The per-iteration realloc then computed bzs.avail_out+1 in unsigned int arithmetic, which wraps to 0 at UINT_MAX, allocating no headroom while bz2 still believes avail_out bytes are available at next_out, so the next decompress round writes past the buffer. Compute the term as (size_t)bzs.avail_out + 1 so the increment is done in size_t and cannot wrap, matching the (size_t) casts already on the same call. Triggering needs a ~4GB crafted input, so there is no portable red/green test. Follow-up to the input guard added in #22242.