Imager::File::GIF versions through 1.002 for Perl allow a heap out of bounds (OOB) write on crafted multi-frame GIF files

Imager::File::GIF versions through 1.002 for Perl allow a heap out of bounds (OOB) write on crafted multi-frame GIF files.

Imager::File::GIF's i_readgif_multi_low allocates a single per-row buffer GifRow sized for the GIF's global screen width 'SWidth' and reuses it across every image in the file.

The page-match branch validates Image.Width + Image.Left > SWidth before each DGifGetLine write, but the parallel skip-image branch at imgif.c:790-805 calls DGifGetLine(GifFile, GifRow, Width) with no such check.