Reject TGA images whose declared size cannot fit the input stream (PR #26761)

MarkLee131

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Jul 31, 2026, 4:28:15 AM (4 days ago) Jul 31

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Two changes to src/common/imagtga.cpp:

Reject a header whose declared image size cannot fit the stream, before either allocation. Uncompressed types have to fit exactly. The RLE types are allowed 128:1, since a packet costs 1 + pixelSize input bytes and yields at most 128 * pixelSize output bytes. The check is skipped when GetLength() returns no usable value, so non-seekable streams are unaffected.
Check LastRead() after the header read and after the three uncompressed bulk reads, so a truncated file fails instead of loading. imagpcx.cpp has done this since #26624. DecodeRLE() already validated its own reads, which is why the RLE paths were already rejecting these files.

wxTGAHandler::DoCanRead() gets the same header check, since it was reading an unfilled hdr for streams shorter than 18 bytes.

Two regression tests in tests/image/image.cpp: Both fail on d5aacc4712 and pass with this commit. Also verified against the 3.3.3 release, where src/common/imagtga.cpp is byte-identical to master.

You can view, comment on, or merge this pull request online at:

https://github.com/wxWidgets/wxWidgets/pull/26761

Commit Summary

9576af5 Reject TGA images whose declared size cannot fit the input stream

File Changes

(2 files)

M src/common/imagtga.cpp (37)
M tests/image/image.cpp (82)

Patch Links:

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VZ

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Aug 1, 2026, 8:01:34 AM (3 days ago) Aug 1

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vadz left a comment (wxWidgets/wxWidgets#26761)

Thanks for fixing this, will merge soon and backport to 3.2.

FWIW I think it would be better/simpler to use ReadAll() instead of Read() followed by LastRead() check, but this is hardly critical.

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VZ

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Aug 1, 2026, 8:05:39 AM (3 days ago) Aug 1

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Closed #26761 via a546a7c.

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