Bound the HEIF meta box allocation by the file size - #23201
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exif_scan_HEIF_header() allocated box.size - box_header_size with only a lower bound, so a 37-byte file could claim a 128MB meta box and force the allocation before any read is attempted. The second allocation in the same block is already bounded by pos.size < ImageInfo->FileSize; apply the same bound to the first. Closes phpGH-23201
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exif_scan_HEIF_header()takes the meta box size straight from the file and allocates it with only a lower bound of 36, so a 37-byte HEIF claiming a 128MB box forces that allocation before a single byte is read.memory_limitstops it, so this is hardening rather than a vulnerability, but the same block already bounds its second allocation bypos.size < ImageInfo->FileSizeand the first one should match.With memory_limit=32M that is "Allowed memory size of 33554432 bytes exhausted (tried to allocate 134217720 bytes)" from a 37-byte file. PHP-8.4 has no HEIF parser, so this starts at 8.5.