Hi Diego,
> I discovered the following floating point exception in libswscale/utils.c:
>
> $ ./avconv -i fpe.jpg out.jpg
> avconv version 0.8.21, Copyright (c) 2000-2014 the Libav developers
> built on Dec 12 2017 14:57:35 with gcc 7.2.1 20171205
> Input #0, image2, from '../samples/output.jpg':
> Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
> Stream #0.0: Video: mjpeg, yuvj444p, 658x61951, 25 tbr, 25 tbn, 25 tbc
> Incompatible pixel format 'yuvj444p' for codec 'mjpeg', auto-selecting format
> 'yuvj420p'
> [buffer @ 0x60a0000002a0] w:658 h:61951 pixfmt:yuvj444p
> [avsink @ 0x60a0000003e0] auto-inserting filter 'auto-inserted scaler 0'
> between the filter 'src' and the filter 'out'
> [scale @ 0x60a000000520] w:658 h:61951 fmt:yuvj444p -> w:658 h:61951
> fmt:yuvj420p flags:0x4
> ASAN:DEADLYSIGNAL
> =================================================================
> ==21916==ERROR: AddressSanitizer: FPE on unknown address 0x561e62fa19cc (pc
> 0x561e62fa19cc bp 0x7fff06ec4300 sp 0x7fff06ec4130 T0)
> #0 0x561e62fa19cb in initFilter libswscale/utils.c:504
> #1 0x561e62fa6b72 in sws_init_context libswscale/utils.c:986
> #2 0x561e62fa91c8 in sws_getContext libswscale/utils.c:1131
> #3 0x561e61f8a6f0 in config_props libavfilter/vf_scale.c:215
> #4 0x561e61f62cbc in avfilter_config_links libavfilter/avfilter.c:191
> #5 0x561e61f67e2c in ff_avfilter_graph_config_links
> libavfilter/avfiltergraph.c:120
> #6 0x561e61f69074 in avfilter_graph_config libavfilter/avfiltergraph.c:245
> #7 0x561e61f23cb3 in configure_video_filters
> /home/hle/Development/C/libav/libav-0.8.21/avconv.c:617
> #8 0x561e61f38641 in transcode_init
> /home/hle/Development/C/libav/libav-0.8.21/avconv.c:2475
> #9 0x561e61f3a800 in transcode
> /home/hle/Development/C/libav/libav-0.8.21/avconv.c:2680
> #10 0x561e61f4c1a7 in main
> /home/hle/Development/C/libav/libav-0.8.21/avconv.c:4551
> #11 0x7fdf26779560 in __libc_start_main
> (/lib/x86_64-linux-gnu/libc.so.6+0x20560)
> #12 0x561e61f20ca9 in _start
> (/home/hle/Development/C/libav/libav-0.8.21/avconv+0x17eca9)
ffmpeg has the following check to avoid this situation:
if (!sum) {
av_log(NULL, AV_LOG_WARNING, "SwScaler: zero vector in scaling\n");
sum = 1;
}
This check is not present in any libav version (why ?). Even after an hour
digging into swscale, it is still unclear to me whether libav > 0.8.21 is
affected or not. It would be great if you could have a look at it.
Do you consider this check to be a valid fix for this FPE ?
Regards,
Hugo
--
Hugo Lefeuvre (hle) | www.owl.eu.com
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