Bun.Image: bound ancillary metadata, tolerate bogus ICC markers, align GIF probe with the decoder - #40526
Bun.Image: bound ancillary metadata, tolerate bogus ICC markers, align GIF probe with the decoder#40526robobun wants to merge 4 commits into
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Reject a path string with an interior NUL in the constructor, with the same ERR_INVALID_ARG_VALUE that Bun.file() and node:fs throw. The worker opened the path as a C string, so "secret\0.png" opened "secret". Run libspng with chunk limits (8 MiB per inflated ancillary chunk, 32 MiB total) so an iCCP, zTXt or iTXt that inflates to gigabytes fails the decode instead of filling memory regardless of maxPixels. Cap the ICC profile the pipeline carries at 8 MiB in all three codecs, checked before the profile is copied out of the codec. JPEG cannot hold more than 255 x 65519 bytes of ICC (one-byte sequence counter), and libjpeg-turbo refused to read back the files it wrote past that point. Treat a libjpeg header warning (JWRN_BOGUS_ICC for an ICC marker sequence that does not reassemble) as "no profile" instead of a decode failure. The scan data is intact; only a fatal header error rejects. Make the GIF probe walk to the first Image Descriptor and report those dimensions, which is what the decoder sizes its output from. metadata() and the terminals now agree on maxPixels for GIF.
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Status: ready for review, CI green (Buildkite build 106168 passed at 5758c8f). Reproduced all four behaviours on stock 1.4.1 with the census repros (NUL path opens the prefix, iCCP bomb produces a 64 MiB WebP from a 65 KB PNG, ICC marker sequence fails metadata(), GIF metadata() reports the logical screen). With this branch each one behaves as described in the PR body. The 12 new tests in test/js/bun/image/image-adversarial.test.ts fail on stock bun and pass with the debug build. Follow-up commits after the first review: dead |
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Included review availability: Your plan provides up to 5 included reviews per hour; 0 remain after this review. WalkthroughChangesImage decoding now rejects embedded-NUL paths, bounds ICC and PNG ancillary metadata, shares JPEG header parsing, and aligns GIF probing with decoded frame dimensions. Adversarial tests cover these validation and metadata behaviors. Image safety and decode consistency
Suggested reviewers: Merge Risk: 🔵 Low · up to The PR is mergeable with explicit owner follow-up: the added GIF test changes the process-global image backend without restoring it, which can make later tests order-dependent and cause unrelated test failures. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Inline comments:
In `@test/js/bun/image/image-adversarial.test.ts`:
- Around line 981-984: Restore the original Bun.Image.backend value after the
test completes, including when an assertion fails; update the test around its
Bun.Image.backend assignment while preserving the existing maxPixels assertions.
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src/runtime/image/Image.rssrc/runtime/image/README.mdsrc/runtime/image/codec_gif.rssrc/runtime/image/codec_jpeg.rssrc/runtime/image/codec_png.rssrc/runtime/image/codec_webp.rssrc/runtime/image/codecs.rstest/js/bun/image/image-adversarial.test.ts
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Beyond the inline nit, I also checked the 9 MiB iCCP test's .rejects expectation — 9 MiB is under the 32 MiB cache limit but exceeds the 8 MiB per-chunk cap (MAX_CHUNK_BYTES), so libspng returns SPNG_ECHUNK_LIMITS and the decode rejects rather than silently dropping the profile; and the spng_set_chunk_limits comment in codec_png.rs against libspng's actual limit semantics.
Extended reasoning...
The two candidates ruled out this run were both about whether the new PNG chunk limits behave as the code and tests claim. The 9 MiB iCCP test looked suspect because 9 MiB < 32 MiB (MAX_CHUNK_CACHE_BYTES), but it is above the 8 MiB per-chunk cap so SPNG_ECHUNK_LIMITS fires and the test's rejection expectation is sound. The MAX_CHUNK_BYTES comment's "decompressed size" wording was also checked against libspng's limit application. Neither turned into a finding; noting them here so a human reviewer doesn't re-tread the same ground.
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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src/runtime/image/codec_jpeg.rs— nit:pub(crate)on tj3DecompressHeader/tj3Get/TJPARAM_JPEGWIDTH/TJPARAM_JPEGHEIGHT is now dead — codecs::probe was their only external caller and it now goes through read_header. sweep:pub\(crate\) (fn tj3(Get|DecompressHeader)|const TJPARAM_JPEG)Extended reasoning...
codecs.rs's JPEG probe branch previously called
jpeg::tj3DecompressHeader,jpeg::tj3Get,jpeg::TJPARAM_JPEGWIDTHandjpeg::TJPARAM_JPEGHEIGHTdirectly, which is why those four items carrypub(crate). This PR rewires that call site tojpeg::read_header(handle.as_ptr(), bytes)(codecs.rs:370) and a repo-wide grep forjpeg::(tj3|TJPARAM)now returns nothing — the visibility became dead in the same commit that made it dead. REVIEW.md's "Delete dead code in the same PR that makes it dead" applies (public items escape dead-code lints, so the compiler won't flag it). Droppub(crate)from the two extern fns at lines 18-19 and the two constants at lines 109-110 so the module surface matches what codecs.rs actually consumes (Handle + read_header).Verification: nit — The four
pub(crate)items are now module-private in effect. Basecodecs.rswas the only external caller (jpeg::tj3DecompressHeader,jpeg::tj3Get,jpeg::TJPARAM_JPEGWIDTH,jpeg::TJPARAM_JPEGHEIGHT); this PR replaces that call site with(w, h) = jpeg::read_header(handle.as_ptr(), bytes)?(codecs.rs diff, probe's Jpeg arm). A repo-wide grep forjpeg::(tj3|TJPARAM)now returns no
codecs::probe went through tj3DecompressHeader, tj3Get and the two TJPARAM_JPEG* constants directly. It now calls jpeg::read_header, so these are module-private again.
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Addressed the visibility nit in d6357da: The 9 MiB iCCP reading is right as well: it is over the 8 MiB per-chunk cap, so libspng returns |
…ng (#43812) ### Problem - `Bun.Image` throws `ERR_IMAGE_DECODE_FAILED` for a JPEG that libjpeg-turbo decodes with only a warning, such as junk before a marker or truncation. - TurboJPEG returns -1 for a fatal error and for a completed call that warned. `codec_jpeg.rs` failed on every -1. - The same function ignored the return of `tj3SetCroppingRegion`, its bound on rows. A 2x64 lossless JPEG resized to 2x50 wrote 8 rows past the buffer. ### Fix - `Handle::completed` accepts a -1 when TurboJPEG's warning flag is set. `patches/libjpeg-turbo/fatal-clears-warning.patch` clears that flag on every fatal exit, where upstream keeps it, and adds the accessor that reads it. A build without the patch fails to link. - A refused region now decodes unscaled with pitch 0, so `TJPARAM_MAXPIXELS` bounds the bytes written. - The EXIF orientation reader skips the junk that libjpeg skips, so an accepted file keeps its rotation. - Verified: 39 new tests, 26 fail on 1.4.3-canary. Self-reviewed: 12 concerns raised, 10 addressed. Not done: an upstream libjpeg-turbo issue. ### Background - libjpeg warns about corrupt data that it decodes around. A fatal error exits through `longjmp`. - The output `Vec` is uninitialised capacity (#39417). Its length is set after a completed decode. ### Downsides - A corrupt or truncated JPEG now resolves where it threw before. A header with no scan data decodes to grey. #40118 asks for strictness. - The accept path depends on a libjpeg-turbo patch. - A resized lossless JPEG, or one with unusual sampling factors, decodes at full size. <details><summary>Notes</summary> **Rule.** If libjpeg-turbo finishes the decode, `Bun.Image` returns the pixels. If libjpeg-turbo hits a fatal error, `Bun.Image` throws, also when a warning came first. This is the line `djpeg` draws between exit status 2 and exit status 1. **Comparison with `djpeg`** (built from the same libjpeg-turbo 3.2.0 source without SIMD, 96x64 q90 fixtures, baseline and progressive gave the same results). Accept and reject match djpeg's exit status at every cut of both files. The pixels match for the files below. Over every cut, 17 of 1214 baseline and 46 of 812 progressive decodes differ from that djpeg, only in the block where the data ends, and none differ when Bun runs with `JSIMD_FORCENONE=1`: libjpeg's SIMD and C IDCT disagree on the out-of-range coefficients of a half-decoded block. | file | djpeg | this branch | | --- | --- | --- | | 16 junk bytes before EOI | exit 2, "13 extraneous bytes before marker 0xd9" | decodes, pixels identical to djpeg | | EOI removed | exit 2, "Premature end of JPEG file" | decodes, identical | | truncated at 95% / 60% | exit 2, "Premature end of JPEG file" | decodes, identical | | cut right after the first SOS header | exit 2 | decodes, identical | | 16 junk bytes + SOF5 after the first scan | exit 1 | `ERR_IMAGE_DECODE_FAILED` | | SOF5 after the first scan | exit 1, "Unsupported JPEG process: SOF type 0xc5" | `ERR_IMAGE_DECODE_FAILED` | **sharp 0.34.5 on the same files.** The default `failOn: "warning"` accepts junk before EOI in a baseline file (libvips never reads to EOI there), rejects it in a progressive file, and rejects truncated and EOI-less files ("premature end of JPEG image"). `failOn: "none"` accepts all of them. **The trap.** `my_emit_message()` in `turbojpeg.c` sets `jerr.warning` and nothing clears it. A progressive JPEG with junk bytes and then an SOF5 marker before the second scan warns, then fails inside `jpeg_start_decompress` before any row is output. `tj3Decompress8` returns -1 with `TJERR_WARNING`. With the Rust change alone (patch removed from `scripts/build/deps/libjpeg-turbo.ts`), "warning, then a fatal error after the first scan: rejects" fails with "Received promise that resolved" for both fixtures. Upstream has the same flag handling at 3.2.0 and at main (b33c60b4). There is no upstream issue. **Why a patch and not a zero-fill or a sentinel.** The decode keeps the `with_capacity` fast path from #39417, with no memset per decode. A zero-filled buffer alone returns a black image for a warning-then-fatal file, which the request rules out. An alpha sentinel cannot cover the CMYK output format, which has no constant byte. The patch is two hunks at the `bailout:` labels of `tj3DecompressHeader` and `tj3Decompress8`: `retval` is non-zero there only after a `longjmp` or a `THROW`. **The accessor.** `codec_jpeg.rs` reads the flag through `tj3BunCompletedWithWarning()`, which the patch adds, and no longer calls `tj3GetErrorCode()`. With the patch removed from the list the build stops at `ld.lld: error: undefined symbol: tj3BunCompletedWithWarning`, so a `--local-deps` checkout without the patch cannot produce a binary that reads a fatal call as a warning. With only the bailout hunks removed (checked at dc12c3a, where the same flag was read through `tj3GetErrorCode()`), four tests fail: the two junk plus SOF5 cases, the progressive file cut inside the DHT or SOS after its first scan, and the 2-component header. **EXIF.** `exif.rs` walks the segments on its own to find the orientation. It stopped at the first byte that was not 0xFF, so a file with junk between APP0 and APP1, which the decoder now accepts, came out unrotated. The walk now skips what `next_marker()` skips: bytes that are not 0xFF, and 0xFF00. Junk between SOI and the first marker never reaches the decoder, because the format sniffer wants `FF D8 FF`. **Call order.** `tj3Set*`, `tj3SetCroppingRegion`, `tj3SetScalingFactor` and `tj3GetICCProfile` reset the warning flag (`GET_TJINSTANCE`). `tj3Get` does not. `Handle::completed` runs straight after each decompress call. **Review comments not taken.** A scaled decode for a stream with unknown subsampling: with the region refused only `TJPARAM_MAXPIXELS` limits the second parse, and it checks the unscaled product, so at 1/8 an 8x8 header (1x1 buffer) lets a 1x64 second parse write 1x8. A strict default for truncated files: see the next paragraph. **To reject truncated input instead.** A missing EOI and truncated scan data are the same warning (`JWRN_JPEG_EOF`), and TurboJPEG exposes only the text of the first warning, so a default that rejects missing data but accepts a missing EOI needs a larger patch that classifies warning codes and reads `coef_bits` for progressive files. The cheap variant: Turn the `JWRN_JPEG_EOF` warning in `fill_mem_input_buffer` (`jdatasrc-tj.c`) into a fatal error in the same patch. EOI-less files then reject too, as in sharp's default. **The cropping region.** `tj3Decompress8` parses the header a second time and takes the row count from that parse, so the caller bounds the writes with the pixel count, the pitch and the region. The review of this diff found the refused-region hole. It is not new (released bun returns the wrong pixels for the same input, and a debug build aborts under ASAN), but the accept path reaches it more easily: a lossless JPEG with a header warning used to be rejected at `metadata()`. The same call also refuses a stream whose sampling factors are outside TurboJPEG's table, which the fix covers. A mid-decode mutation of the input buffer can still make the second parse disagree, which is #43792's subject; with pitch 0 the bytes stay inside the buffer. **The fill.** libjpeg writes flat grey for a block with no data, in every kind of file: (128,128,128), or (64,64,64) after the CMYK conversion. A progressive file has data for every block once its first scan is complete, so a later cut costs detail and no area. **Self-review.** Four reviewers (the C patch, the Rust side, the tests, the written claims) raised 12 concerns. Found and fixed: the refused cropping region (the overflow above), the same call's second refusal (unknown subsampling), two tests that passed without the patch (replaced by a progressive file cut inside the DHT or SOS after its first scan, and a 2-component header that fails the colorspace check after a warning), truncation tests whose cut could land inside a marker segment, a docs sentence that was wrong for a cut inside the first progressive scan and for CMYK, the djpeg comparison (scoped above), and comments that named the patch's effect for more functions than it covers. The decode that spins when the second parse is shorter is #43792's. One test-runtime concern needed no change (no test is over 1.5 s on a debug build). Not done: the vendoring rule asks for an upstream issue link, and no upstream issue exists. The patch header cites upstream's own precedent instead: `my_progress_monitor()` already clears the flag before its `longjmp`. **Related open PRs.** #40526 adds a header-only version of the same check (it relies on the width and height test to catch a fatal error). #40120 makes the fast Huffman path emit `JWRN_HUFF_BAD_CODE` so that the decode rejects. After this PR a warning no longer rejects, so #40120 has no effect. **Docs.** `docs/runtime/image.mdx`, the `ErrorCode` JSDoc in `bun.d.ts`, and `src/runtime/image/README.md` describe the behaviour and the patch. **Unwritten bytes.** The alpha check in the truncation tests is weak inside one process: the allocator often hands back a block that held an earlier decode, so a row libjpeg never wrote can still read as opaque. "an accepted JPEG decode commits no byte that libjpeg did not write" runs the same cuts in a child with `ASAN_OPTIONS=malloc_fill_byte=90:max_malloc_fill_size=1073741824` (ASAN builds only). Every new allocation then starts as 0x5A. With the two bailout hunks removed and the accessor kept, the progressive file with junk and SOF5 after its first scan reads "has unwritten bytes" there. **The refused region and scaling.** The lossless fixture cannot pin the scaling reset in the refused-region branch, because libjpeg ignores the factor for a lossless stream. A second fixture does: a JPEG with luma sampling 3x1 (`cjpeg -sample 3x1,1x1,1x1`, 748 bytes), which TurboJPEG also refuses a cropping region for and which libjpeg does scale. With the reset removed, the lossless tests still pass, "a resize shows the picture of the full-size decode" fails, and the ASAN fill test reads "has unwritten bytes" for that file: libjpeg packs the scaled rows into the full-size buffer and three quarters of it stay unwritten. **Test shape.** The fixtures are encoded in the test, except the lossless one: Bun's encoder writes baseline or progressive only, so those 360 bytes are a TurboJPEG encode, in base64. A cut at a fraction of the file would land inside a marker segment for about a fifth of the lengths the encoder can produce, which is a fatal error and not this warning, so the truncation tests cut inside a scan's entropy data. The lossless decode runs in a child process: without the fix it aborts under ASAN, which would take the whole test file with it. **Suites run on the debug build:** `image-adversarial.test.ts` (98 pass), `image.test.ts` (103 pass, 5 skip), `image-kernels.test.ts` (37 pass), `image-vs-sharp.test.ts` (29 pass). `cargo clippy -p bun_runtime` reports nothing for the touched files. The gate's fail-before was run by hand (`git checkout --no-overlay origin/main -- src/ packages/`): 23 of 93 tests failed at that commit and the runner survived. </details> <!-- robobun:evidence:begin --> --- **no test proof** · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/bun/image/image.test.ts, test/js/bun/image/image-adversarial.test.ts <!-- robobun:evidence:end -->
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Problem
new Bun.Image("secret-no-ext\0.png")openedsecret-no-ext. The worker passes the path toopenatas a C string (Image.rs:1566), so a JS-side extension check on the string is bypassed.Bun.file()andnode:fsreject the same string withERR_INVALID_ARG_VALUE. Under debug asserts this ispanic: ZStr::as_cstr: interior NUL would truncate the C view.maxPixels: 64.codec_png.rsnever setspng_set_chunk_limits, and the inflated profile was copied into every output (.webp()emitted a 1 GiB file). A profile over 255 x 65519 bytes made.jpeg()write a file Bun could not read back, and any JPEG whoseICC_PROFILEmarkers did not reassemble failed every terminal, includingmetadata().metadata()read the Logical Screen Descriptor while the decoder sized its output and ran themaxPixelsguard from the first Image Descriptor. A 1x1 screen wrapping a 16383x16383 frame reported 1x1 and decoded to 1 GiB.Fix
Valid::path_null_bytes, the checkBun.file()uses, and throwsERR_INVALID_ARG_VALUE.codec_png.rssets libspng chunk limits (8 MiB per inflated chunk, 32 MiB total); a chunk over the cap fails the decode.codecs::MAX_ICC_PROFILE_BYTES(8 MiB) is checked in all three decoders before the profile is copied out, and once more incodecs::encode. 8 MiB is libpng's user-chunk default and fits under the JPEG ceiling.codec_jpeg::read_headeraccepts a header that returned -1 withtj3GetErrorCode == TJERR_WARNING: the SOF fields are valid, the profile is absent. The full decode is unchanged and still fails on any warning fromtj3Decompress8.codec_gif::parse_headeris split out ofdecodeand the probe uses it, so both report the frame's dimensions.test/js/bun/image/image-adversarial.test.ts(12 new tests fail on stock 1.4.1, pass with the fix). Also all oftest/js/bun/image/.Background
Bun.Imagedecodes into RGBA8 and re-encodes. The ICC profile (JPEG APP2, PNG iCCP, WebP ICCP) travels with the pixels untouched because the pipeline does no colour conversion (Bun.Image strips ICC profile #30197).maxPixelsguards the RGBA buffer only, so it never sees that memory.tj3GetErrorCodetells them apart.Notes
Ledger items from the fuzz census: #18181 (NUL path), #18182 (iCCP bomb), #18183 (ICC marker overflow), #18184 (GIF probe vs decode).
Design notes:
SPNG_ECHUNK_LIMITSas fatal even on ancillary chunks (read_chunksonly recovers from the listed per-chunk errors), so an over-cap iCCP fails the decode rather than being dropped the way libpng does. Patching libspng to discard the chunk instead is possible but not done here. In practice the band between "real profile" (under 4 MB) and the 8 MiB cap is empty.jpeg_read_headerinsidetj3Decompress8, which does not calljpeg_read_icc_profile, soJWRN_BOGUS_ICCdoes not fire there and the decode succeeds. Other header warnings (extraneous bytes, JFIF major version) do fire again there and still reject, as before. The only observable change for decode is the ICC case;metadata()is now tolerant of all header warnings.metadata()and is rejected by anymaxPixelsbelow that, consistently with the terminals.Stock 1.4.1 before / debug build after, on the census repros:
Suites run:
test/js/bun/image/image-adversarial.test.ts,test/js/bun/image/image.test.ts,test/js/bun/image/image-kernels.test.ts,test/js/bun/image/image-vs-sharp.test.ts(235 pass, 2 platform skips, 0 fail).cargo clippy -p bun_runtimeclean.no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/bun/image/image-adversarial.test.ts