[Xvid-devel] 1.3.5 segfault in check_cpu_features (xvidcore/src/utils/x86_asm/cpuid.asm:97)

[Michael Militzer]

Hi,

does this crash happen also outside of ffmpeg, so e.g. when you run  
the xvid_encraw example?

Best regards,
Michael


Quoting Dominik 'Rathann' Mierzejewski <dominik at greysector.net>:

> Dear developers,
> on Fedora 29, we started getting segmentation faults in
> check_cpu_features. Here's a downstream bug report:
> https://bugzilla.rpmfusion.org/show_bug.cgi?id=5141
>
> Same nasm version was used to build both on Fedora 28 and 29.
> There are differences in gcc version (8.0.1 vs. 8.2.1), binutils
> (2.29.1 vs. 2.31.1). Links to each build:
> http://koji.rpmfusion.org/koji/buildinfo?buildID=6763 (F28)
> http://koji.rpmfusion.org/koji/buildinfo?buildID=8508 (F29)
>
> The issue can be reproduced with ffmpeg. Here's the backtrace:
> $ coredumpctl gdb ffmpeg
> ...
> Core was generated by `ffmpeg -i arrival-tlr2_h1080p.mov -c:a copy   
> -c:v libxvid out.mp4'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x00007f5e62980920 in check_cpu_features () from /lib64/libxvidcore.so.4
> [Current thread is 1 (Thread 0x7f5e61523e80 (LWP 23309))]
> (gdb) where
> #0  0x00007f5e62980920 in check_cpu_features () from /lib64/libxvidcore.so.4
> #1  0x00007f5e628fa12b in detect_cpu_flags () at ../../src/xvid.c:156
> #2  0x00007f5e628fb235 in xvid_gbl_init (init=0x7fff3250c044,   
> init=0x7fff3250c044) at ../../src/xvid.c:792
> #3  xvid_global (handle=handle at entry=0x0, opt=opt at entry=0,   
> param1=param1 at entry=0x7fff3250c044, param2=param2 at entry=0x0)
>     at ../../src/xvid.c:816
> #4  0x00007f5e653e9157 in xvid_encode_init (avctx=0x5566b6afd3c0) at  
>  libavcodec/libxvid.c:458
> #5  0x00007f5e6588414e in avcodec_open2 (avctx=0x5566b6afd3c0,   
> codec=0x7f5e65e82660 <ff_libxvid_encoder>,
>     options=0x5566b6acc2d8) at libavcodec/utils.c:923
> #6  0x00005566b607cfaa in init_output_stream (ost=<optimized out>,   
> error=0x7fff3250c790 "", error_len=1024)
>     at fftools/ffmpeg.c:3473
> #7  0x00005566b607ec31 in reap_filters (flush=0) at fftools/ffmpeg.c:1432
> #8  0x00005566b6061eb0 in transcode_step () at fftools/ffmpeg.c:4597
> #9  transcode () at fftools/ffmpeg.c:4641
> #10 main (argc=<optimized out>, argv=<optimized out>) at   
> fftools/ffmpeg.c:4841
> (gdb)
>
> My CPU is:
> $ lscpu
> Architecture:        x86_64
> CPU op-mode(s):      32-bit, 64-bit
> Byte Order:          Little Endian
> CPU(s):              4
> On-line CPU(s) list: 0-3
> Thread(s) per core:  2
> Core(s) per socket:  2
> Socket(s):           1
> NUMA node(s):        1
> Vendor ID:           GenuineIntel
> CPU family:          6
> Model:               69
> Model name:          Intel(R) Core(TM) i7-4500U CPU @ 1.80GHz
> Stepping:            1
> CPU MHz:             838.433
> CPU max MHz:         3000.0000
> CPU min MHz:         800.0000
> BogoMIPS:            4788.77
> Virtualization:      VT-x
> L1d cache:           32K
> L1i cache:           32K
> L2 cache:            256K
> L3 cache:            4096K
> NUMA node0 CPU(s):   0-3
> Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep   
> mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht  
>  tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs   
> bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni   
> pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr  
>  pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave   
> avx f16c rdrand lahf_lm abm cpuid_fault epb invpcid_single pti ssbd   
> ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad   
> fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm  
>  ida arat pln pts flush_l1d
>
> Any ideas how to debug this?
>
> Regards,
> Dominik
> --
> Fedora   https://getfedora.org  |  RPM Fusion  http://rpmfusion.org
> There should be a science of discontent. People need hard times and
> oppression to develop psychic muscles.
>         -- from "Collected Sayings of Muad'Dib" by the Princess Irulan
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