Heap-buffer-overflow write in FFmpeg EXR dwa_uncompress

When decoding an OpenEXR file that uses DWAA or DWAB compression, there's an implicit assumption that all image channels have the same pixel type (and size), and that if there are four channels, the first four are "B", "G", "R" and "A". The channel parsing code can be found in decode_header. The buffer td->uncompressed_data is allocated in decode_block based on the xsize, ysize and computed current_channel_offset. The function dwa_uncompress then assumes at [5] that if there are 4 channels, these are "B", "G", "R" and "A", and in the calculations at [6] and [7] that all channels are of the same type, which matches the type of the main color channels. If we set the main color channels to a 4-byte type and add duplicate or unknown channels of the 2-byte EXR_HALF type, then the addition at [7] will increment the pointer by 4-bytes * xsize * nb_channels, which will exceed the allocated buffer. We recommend upgrading to version 8.0 or beyond.

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跨界内存写

OpenEXR 安全漏洞

OpenEXR是Academy Software Foundation开源的一种高动态范围图像（HDR）文件格式的开放标准。 OpenEXR存在安全漏洞，该漏洞源于DWAA或DWAB压缩解码时假设所有图像通道具有相同像素类型，可能导致缓冲区溢出。

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