fix(dds): reject corrupt bytes-per-pixel before it forces a huge allocation#5286
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…cation A DDS file with a garbage pixel-format bpp field (e.g. fmt.bpp ~2.5e9) yields a native bytes-per-pixel (m_Bpp) of hundreds of millions. internal_readimg() then does `new uint8_t[width * m_Bpp]`, a multi-GB allocation that OOMs under the fuzzer's RSS limit. The core resolution/imagesize limits do not catch this: they only see the small output ImageSpec, not the native pixel size, and the existing fmt.bpp check is gated on RGB/LUM/YUV/ALPHA flags that a corrupt header can simply omit. Validate m_Bpp for uncompressed formats right after it is computed in open(): the largest real uncompressed DDS/DXGI pixel is 128-bit (16 bytes), so anything outside [1,16] is a corrupt header and is rejected before any allocation. The check is confined to uncompressed formats because m_Bpp is neither set nor used for compressed (block) formats, which size their data via GetStorageRequirements. Add the fuzzer reproducer as testsuite/dds/src/crash-bpp.dds. crash-1635.dds now reports this error slightly earlier than the prior "bit depth" message; update the reference accordingly. Assisted-by: Claude Code / Claude Opus 4.8 Signed-off-by: Larry Gritz <lg@larrygritz.com>
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A DDS file with a garbage pixel-format bpp field (e.g. fmt.bpp ~2.5e9) yields a native bytes-per-pixel (m_Bpp) of hundreds of millions. internal_readimg() then does
new uint8_t[width * m_Bpp], a multi-GB allocation that OOMs. The core resolution/imagesize limits do not catch this: they only see the small output ImageSpec, not the native pixel size, and the existing fmt.bpp check is gated on RGB/LUM/YUV/ALPHA flags that a corrupt header can simply omit.Validate m_Bpp for uncompressed formats right after it is computed in open(): the largest real uncompressed DDS/DXGI pixel is 128-bit (16 bytes), so anything outside [1,16] is a corrupt header and is rejected before any allocation. The check is confined to uncompressed formats because m_Bpp is neither set nor used for compressed (block) formats, which size their data via GetStorageRequirements.
Assisted-by: Claude Code / Claude Opus 4.8