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Scott Boudreaux
d4673a97ac
Fix two buffer overreads in the PowerPC yuv2planeX SIMD paths
that cause daily FATE checkasm-sw_scale ASAN failures on both
ppc64 (G5, altivec) and ppc64le (POWER9, VSX):
1. VSX LOAD_FILTER: vec_vsx_ld(joffset, filter) reads 16 bytes
at the given byte offset. When joffset >= filterSize*2 - 14
(e.g. joffset=30 for filterSize=16), this reads up to 14 bytes
past the 32-byte filter array. Fix by replacing the vector
load with vec_splats(f[j]) which only reads the single int16_t
element needed (the result is splatted to all lanes anyway).
2. GET_LS look-ahead overread: yuv2planeX_8_16 calls
yuv2planeX_8 twice per filter tap. Each call's GET_LS macro
speculatively loads the next 16-byte vector for pipelining.
On the second call, this look-ahead reads 16 bytes past the
last valid source element. Fix by tightening the SIMD loop
bound from (dstW - 15) to (dstW - 23), ensuring the farthest
speculative load stays within src[j][0..dstW-1]. The scalar
fallback handles the remaining 16-23 trailing pixels.
The ASAN reports from FATE:
ppc64 (altivec): stack-buffer-overflow in yuv2planeX_8_16_altivec
at swscale_ppc_template.c:56
ppc64le (VSX): unknown-crash in yuv2planeX_8_16_vsx
at swscale_ppc_template.c:52
Signed-off-by: Scott Boudreaux <scott@elyanlabs.com>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.