enforce limit on area of deep tiles to prevent excessive memory use #939
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Signed-off-by: Peter Hillman <peterh@wetafx.co.nz>
meshula
reviewed
Feb 26, 2021
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| if(_data->maxSampleCountTableSize > std::numeric_limits<unsigned int>::max()) | ||
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| THROW(IEX_NAMESPACE::ArgExc, "Version " << _data->header.version() << " not supported for deeptiled images in this version of the library"); |
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was this meant to say "tiles requiring over two gigabytes for the sample count table are not supported"?
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| if(_data->maxSampleCountTableSize > std::numeric_limits<unsigned int>::max()) | ||
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| THROW(IEX_NAMESPACE::ArgExc, "Deep tile size exceeds maximum permitted area"); |
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well, that was embarrassing! Exception message now revised
Signed-off-by: Peter Hillman <peterh@wetafx.co.nz>
meshula
approved these changes
Feb 26, 2021
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This change enforces a hard limit on deep tile sizes, so that xSize*ySize must be less than 2^30, approx 1gigapixel per tile.
This would require more than 2GB of memory to allocate the 'sample count' table. This is not possible on 32 bit architectures, and causes excessive memory allocation on 64 bit architectures.
It is assumed that 'real' files will have much smaller deep tiles (1024x1024 pixels is already quite large), so files that contain tileDescription attributes indicating very large tiles are either corrupt or malicious.
This change is to Deep tiles only. A similar limit is already imposed on regular Tiled images, since the format cannot store compressed tiles with more than 2^31 bytes.
Address:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31390
(additionally, a bug in Imf::CheckFile meant that the large tiles were not being detected)
Signed-off-by: Peter Hillman peterh@wetafx.co.nz