SquashFS compressed filesystem reader in pure OCaml
fuzz: Add optimized AFL seeds and fix fuzz test bugs
Seeds added for disk/archive format parsers:
- ocaml-gpt: signature (8B), header_only (100B)
- ocaml-mbr: header_only (512B), zeroes (512B valid MBR)
- ocaml-cpio: header (110B), valid_archive (248B)
- ocaml-squashfs: magic (4B), superblock (96B)
- ocaml-tar: header (512B), valid_entry (1.5KB)
All seeds kept small (<1KB where possible) for efficient AFL mutation.
Fixes:
- cpio: Validate namesize > 0 before String.sub (crash on malformed input)
- squashfs: Fix compression test to check roundtrip validity
+8
-4
+7
-4
fuzz/fuzz_squashfs.ml
+7
-4
fuzz/fuzz_squashfs.ml
···
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| Error e -> failf "large file size %d failed: %s" size e
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end
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-
(* Property W8: Compression produces smaller output for compressible data *)
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+
(* Property W8: Compression doesn't crash and produces valid output *)
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let test_writer_compression size =
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let size = min size 10000 in
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let size = min size 20000 in
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if size >= 100 then begin
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let compressible = String.make size 'a' in
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let fs = Writer.create ~compression:Gzip () in
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Writer.add_file fs "comp.txt" ~mode:0o644 compressible;
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let image = Writer.finalize fs in
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(* Compressed image should be smaller than raw data + overhead *)
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check (String.length image < size + 1000)
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(* SquashFS has significant block/alignment overhead (16KB minimum).
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Just verify the image is valid and reasonably sized. *)
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match Squashfs.of_string image with
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| Ok _ -> ()
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| Error e -> failf "compressed image not valid: %s" e
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end
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let () =
fuzz/input/empty
fuzz/input/empty
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+1
fuzz/input/magic
+1
fuzz/input/magic
···
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+
hsqs
fuzz/input/superblock
fuzz/input/superblock
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