tag/Id3Load: cap ID3v2 tag-size allocation at 4 MB#2534
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ReadId3Tag() allocates a buffer sized by the ID3v2 syncsafe size field before validating that the file actually contains that many bytes. A crafted 1 KB file with a header claiming ~256 MB forces a ~256 MB heap allocation (256Kx amplification). The sibling tag_id3_riff_aiff_load already caps at 4 MB for the same reason; this applies the same bound to the main ID3v2 path. A remote MPD client with READ permission (the default) can trigger this via the readcomments command pointing at an attacker-controlled HTTP server, causing denial of service through memory exhaustion.
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Backported to v0.24.x: a9ac72b |
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ReadId3Tag() allocates a buffer sized by the ID3v2 syncsafe size field
before validating that the file actually contains that many bytes. A
crafted 1 KB file with a header claiming ~256 MB forces a ~256 MB heap
allocation (256000x amplification). The sibling function
tag_id3_riff_aiff_load already caps at 4 MB for the same reason, but the
main ID3v2 path never got the same bound.
A remote MPD client with the default READ permission can trigger this
via the readcomments command pointing at an attacker-controlled HTTP
server that serves a crafted file, causing denial of service through
memory exhaustion (repeatable across connections, and the SEEK-frame
loop in the same function allows repeated spikes within a single
request).
This adds the same 4 MB cap already used by tag_id3_riff_aiff_load,
placed right after tag_size is computed and before the allocation.