[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #13 from Martin Liška  ---
(In reply to Carl Eugen Hoyos from comment #12)
> Should be fixed:
> http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=10f46815
> https://trac.ffmpeg.org/ticket/7491
> 
> I wonder a little how the FFmpeg developers were supposed to find out about
> this bug...

Good, thanks for mainline fix!

[Bug lto/85132] ffmpeg runtime segfault with lto

[cehoyos at ag dot or.at]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

Carl Eugen Hoyos  changed:

   What|Removed |Added

 CC||cehoyos at ag dot or.at

--- Comment #12 from Carl Eugen Hoyos  ---
Should be fixed:
http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=10f46815
https://trac.ffmpeg.org/ticket/7491

I wonder a little how the FFmpeg developers were supposed to find out about
this bug...

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #11 from Martin Liška  ---
It was changed on trunk in:

commit 371072bf395be11f36ef31bb3cfec06bbfc58597
Author: law 
Date:   Fri Sep 1 16:26:00 2017 +

* varasm.c (bss_initializer_p): Do not put constants into .bss
(categorize_decl_for_section): Handle bss_initializer_p returning
false when DECL_INITIAL is NULL.

* gcc.target/i386/const-in-bss.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@251602
138bc75d-0d04-0410-961f-82ee72b054a4

Note the using an undefined behavior gives optimizer opportunity to optimize to
any way. In this case GCC 7 generated working and GCC 8 not working code in
case of ffmpeg.

[Bug lto/85132] ffmpeg runtime segfault with lto

[manuel.lauss at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #10 from Manuel Lauss  ---
Built with gcc-7.3.0 and LTO it works fine; is this a bug in 7.3.0 instead
then?

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

Martin Liška  changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |INVALID

--- Comment #9 from Martin Liška  ---
So it's really caused by --enable-hardcoded-tables. With that you have in
sinewin.c pre-processed source file:

extern const INTFLOAT __attribute__ ((aligned (32))) ff_sine_960[960];

As you can se, it's const (a.k.a. READONLY). Thus doing a write to it in
ff_sine_window_init causes a segfault.

Thus closing as invalid.

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

Martin Liška  changed:

   What|Removed |Added

 Status|WAITING |ASSIGNED
   Assignee|unassigned at gcc dot gnu.org  |marxin at gcc dot 
gnu.org

--- Comment #8 from Martin Liška  ---
Stupid mistake from me. Now I can reproduce that:

LD_LIBRARY_PATH=./libavcodec/ gdb --args ./ffmpeg -i small.mp4

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #7 from Martin Liška  ---
(In reply to Manuel Lauss from comment #6)
> (In reply to Martin Liška from comment #5)
> > (In reply to Manuel Lauss from comment #4)
> > > (In reply to Martin Liška from comment #3)
> > > > (In reply to Manuel Lauss from comment #2)
> > > > > This is the most minimal ffmpeg config that can trigger the segfault. 
> > > > > The
> > > > > interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" 
> > > > > Player
> > > > > with a standard mp4 video file to trigger it
> > > > > (https://github.com/mpv-player/mpv/archive/v0.27.2.zip)
> > > > 
> > > > Good. so we have minimal set of options for ffmpeg. Now please explain 
> > > > me
> > > > how to build the MPV tool? Is it really needed? Can't one trigger that
> > > > directly with ffmepg? Please upload somewhere the mp4 file so that I can
> > > > reproduce it.
> > > 
> > > The segfault happens during initialization of ffmpeg when mpv player 
> > > starts.
> > > I can also trigger it with firefox on e.g. youtube: it crashes the tab.
> > 
> > Ok, so please download following sample video:
> > http://techslides.com/demos/sample-videos/small.mp4
> > 
> > And try to run ffmpeg to print info:
> > ./ffmpeg -i small.mp4
> > 
> > Does it also segfault?
> 
> Yes, same backtrace, same fault location.

Hm, I put __builtin_abort to:
static av_cold void aac_static_table_init(void)

function. And it's unfortunately called. Probably because:
$ ./ffmpeg -i small.mp4 test.mp3
...
Decoder (codec aac) not found for input stream #0:1

Are you sure the configure options enable the codec (AAC)?

[Bug lto/85132] ffmpeg runtime segfault with lto

[manuel.lauss at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #6 from Manuel Lauss  ---
(In reply to Martin Liška from comment #5)
> (In reply to Manuel Lauss from comment #4)
> > (In reply to Martin Liška from comment #3)
> > > (In reply to Manuel Lauss from comment #2)
> > > > This is the most minimal ffmpeg config that can trigger the segfault. 
> > > > The
> > > > interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" 
> > > > Player
> > > > with a standard mp4 video file to trigger it
> > > > (https://github.com/mpv-player/mpv/archive/v0.27.2.zip)
> > > 
> > > Good. so we have minimal set of options for ffmpeg. Now please explain me
> > > how to build the MPV tool? Is it really needed? Can't one trigger that
> > > directly with ffmepg? Please upload somewhere the mp4 file so that I can
> > > reproduce it.
> > 
> > The segfault happens during initialization of ffmpeg when mpv player starts.
> > I can also trigger it with firefox on e.g. youtube: it crashes the tab.
> 
> Ok, so please download following sample video:
> http://techslides.com/demos/sample-videos/small.mp4
> 
> And try to run ffmpeg to print info:
> ./ffmpeg -i small.mp4
> 
> Does it also segfault?

Yes, same backtrace, same fault location.

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #5 from Martin Liška  ---
(In reply to Manuel Lauss from comment #4)
> (In reply to Martin Liška from comment #3)
> > (In reply to Manuel Lauss from comment #2)
> > > This is the most minimal ffmpeg config that can trigger the segfault. The
> > > interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" 
> > > Player
> > > with a standard mp4 video file to trigger it
> > > (https://github.com/mpv-player/mpv/archive/v0.27.2.zip)
> > 
> > Good. so we have minimal set of options for ffmpeg. Now please explain me
> > how to build the MPV tool? Is it really needed? Can't one trigger that
> > directly with ffmepg? Please upload somewhere the mp4 file so that I can
> > reproduce it.
> 
> The segfault happens during initialization of ffmpeg when mpv player starts.
> I can also trigger it with firefox on e.g. youtube: it crashes the tab.

Ok, so please download following sample video:
http://techslides.com/demos/sample-videos/small.mp4

And try to run ffmpeg to print info:
./ffmpeg -i small.mp4

Does it also segfault?

> 
> 
> ad mpv: unpack, configure with the following line (you need python3):
> CCFLAGS="-O3 -march=znver1 -mtune=znver1 -flto=16 -fno-fat-lto-objects
> -pipe" LINKFLAGS="-O3 -march=znver1 -mtune=znver1 -flto=16
> -fno-fat-lto-objects -pipe -Wl,--no-as-needed" ./waf --prefix=/usr
> --libdir=/usr/lib64 --confdir=/etc/mpv --docdir=/usr/share/doc/mpv-0.27.2
> --htmldir=/usr/share/doc/mpv-0.27.2/html --enable-libmpv-shared
> --disable-libmpv-static --disable-static-build --disable-optimize
> --disable-debug-build --enable-html-build --disable-pdf-build
> --enable-cplugins --disable-zsh-comp --disable-test --disable-android
> --enable-iconv --disable-libsmbclient --enable-lua --lua=luajit
> --disable-javascript --enable-x11  --disable-build-date configure
> 
> ./waf build

How the player knows where to find the built ffmpeg libraries?

[Bug lto/85132] ffmpeg runtime segfault with lto

[manuel.lauss at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #4 from Manuel Lauss  ---
(In reply to Martin Liška from comment #3)
> (In reply to Manuel Lauss from comment #2)
> > This is the most minimal ffmpeg config that can trigger the segfault. The
> > interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" Player
> > with a standard mp4 video file to trigger it
> > (https://github.com/mpv-player/mpv/archive/v0.27.2.zip)
> 
> Good. so we have minimal set of options for ffmpeg. Now please explain me
> how to build the MPV tool? Is it really needed? Can't one trigger that
> directly with ffmepg? Please upload somewhere the mp4 file so that I can
> reproduce it.

The segfault happens during initialization of ffmpeg when mpv player starts.  I
can also trigger it with firefox on e.g. youtube: it crashes the tab.


ad mpv: unpack, configure with the following line (you need python3):
CCFLAGS="-O3 -march=znver1 -mtune=znver1 -flto=16 -fno-fat-lto-objects -pipe"
LINKFLAGS="-O3 -march=znver1 -mtune=znver1 -flto=16 -fno-fat-lto-objects -pipe
-Wl,--no-as-needed" ./waf --prefix=/usr --libdir=/usr/lib64 --confdir=/etc/mpv
--docdir=/usr/share/doc/mpv-0.27.2 --htmldir=/usr/share/doc/mpv-0.27.2/html
--enable-libmpv-shared --disable-libmpv-static --disable-static-build
--disable-optimize --disable-debug-build --enable-html-build
--disable-pdf-build --enable-cplugins --disable-zsh-comp --disable-test
--disable-android --enable-iconv --disable-libsmbclient --enable-lua
--lua=luajit --disable-javascript --enable-x11  --disable-build-date configure

./waf build

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

Martin Liška  changed:

   What|Removed |Added

 Status|UNCONFIRMED |WAITING
   Last reconfirmed||2018-03-31
 Ever confirmed|0   |1

--- Comment #3 from Martin Liška  ---
(In reply to Manuel Lauss from comment #2)
> This is the most minimal ffmpeg config that can trigger the segfault. The
> interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" Player
> with a standard mp4 video file to trigger it
> (https://github.com/mpv-player/mpv/archive/v0.27.2.zip)

Good. so we have minimal set of options for ffmpeg. Now please explain me how
to build the MPV tool? Is it really needed? Can't one trigger that directly
with ffmepg? Please upload somewhere the mp4 file so that I can reproduce it.

[Bug lto/85132] ffmpeg runtime segfault with lto

[manuel.lauss at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #2 from Manuel Lauss  ---
This is the most minimal ffmpeg config that can trigger the segfault. The
interesting switch is "--enabled-hardcoded-tables".  I use the "mpv" Player
with a standard mp4 video file to trigger it
(https://github.com/mpv-player/mpv/archive/v0.27.2.zip)

configure --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64
--docdir=/usr/share/doc/ffmpeg-3.4.2-r1/html --mandir=/usr/share/man
--enable-share
d --cc=x86_64-pc-linux-gnu-gcc --cxx=x86_64-pc-linux-gnu-g++
--ar=x86_64-pc-linux-gnu-ar --optflags=-O3 -ggdb -march=znver1 -mtune=znver1
-flto=16 -fno-fat-lto-objects -pipe --disable-static --enable-avfilter
--enable-avresample --disable-stripping --disable-encoders --disable-indev=v4l2
--disable-outdev=v4l2 --disable-indev=alsa --disable-indev=oss --disable
-indev=jack --disable-outdev=alsa --disable-outdev=oss --disable-outdev=sdl
--disable-bzlib --disable-runtime-cpudetect --disable-debug --disable-gcrypt
--disable-gnutls --disable-gmp --enable-gpl --enable-hardco
ded-tables --disable-iconv --disable-lzma --disable-network --disable-opencl
--disable-openssl --disable-postproc --disable-libsmbclient --disable-ffplay
--disable-sdl2 --disable-vaapi --disable-vdpau --disable-x
lib --disable-libxcb --disable-libxcb-shm --disable-libxcb-xfixes
--disable-zlib --disable-libcdio --disable-libiec61883 --disable-libdc1394
--disable-libcaca --disable-openal --disable-opengl --disable-libv4l2 -
-disable-libpulse --disable-libdrm --disable-libopencore-amrwb
--disable-libopencore-amrnb --disable-libfdk-aac --disable-libopenjpeg
--disable-libbluray --disable-libcelt --disable-libgme --disable-libgsm --disa
ble-mmal --disable-libmodplug --disable-libopus --disable-libilbc
--disable-librtmp --disable-libssh --disable-libspeex --disable-librsvg
--disable-libvorbis --disable-libvpx --disable-libzvbi --disable-appkit --
disable-libbs2b --disable-chromaprint --disable-libflite --disable-frei0r
--disable-libfribidi --disable-fontconfig --disable-ladspa --disable-libass
--disable-libfreetype --disable-librubberband --disable-libzmq
 --disable-libzimg --disable-libsoxr --enable-pthreads --disable-armv5te
--disable-armv6 --disable-armv6t2 --disable-neon --disable-vfp --disable-vfpv3
--disable-armv8 --disable-mipsdsp --disable-mipsdspr2 --disa
ble-mipsfpu --disable-altivec --disable-amd3dnow --disable-amd3dnowext
--disable-fma4 --disable-xop --cpu=znver1 --enable-lto --disable-doc
--disable-htmlpages --enable-manpages

[Bug lto/85132] ffmpeg runtime segfault with lto

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85132

--- Comment #1 from Martin Liška  ---
Hi Manual.

Can you please reduce a bit the configure options. The package requires many
libraries as dependency. How do you invoke ffmpeg to expose the crash?