[Bug 1849615] Re: WebRTC-related crashes

Thu Oct 24 10:07:06 UTC 2019

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On 2019-10-24T07:07:08+00:00 Gabriele Svelto wrote:

This bug is for crash report bp-abe63a7e-7862-4e4d-b2f7-313140191023.

```
Top 10 frames of crashing thread:

0 libc-2.27.so raise /build/glibc-OTsEL5/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51
1 libc-2.27.so abort /build/glibc-OTsEL5/glibc-2.27/stdlib/abort.c:79
2 libc-2.27.so __libc_message /build/glibc-OTsEL5/glibc-2.27/libio/../sysdeps/posix/libc_fatal.c:181
3 libc-2.27.so __fortify_fail_abort /build/glibc-OTsEL5/glibc-2.27/debug/fortify_fail.c:33
4 libc-2.27.so __fortify_fail /build/glibc-OTsEL5/glibc-2.27/debug/fortify_fail.c:44
5 libc-2.27.so __chk_fail /build/glibc-OTsEL5/glibc-2.27/debug/chk_fail.c:28
6 libc-2.27.so __fdelt_chk /build/glibc-OTsEL5/glibc-2.27/debug/fdelt_chk.c:25
7 libxul.so webrtc::videocapturemodule::DeviceInfoLinux::EventCheck /build/firefox-WlAST4/firefox-69.0.2+build1/media/webrtc/trunk/webrtc/modules/video_capture/linux/device_info_linux.cc:92
8 libxul.so webrtc::videocapturemodule::DeviceInfoLinux::ProcessInotifyEvents /build/firefox-WlAST4/firefox-69.0.2+build1/media/webrtc/trunk/webrtc/modules/video_capture/linux/device_info_linux.cc:133
9 libxul.so webrtc::videocapturemodule::DeviceInfoLinux::InotifyProcess /build/firefox-WlAST4/firefox-69.0.2+build1/media/webrtc/trunk/webrtc/modules/video_capture/linux/device_info_linux.cc:166

```

This crash is happening in the Ubuntu-packaged version of Firefox. It
seems to affect 64-bit users only. I'll file a bug on Ubuntu's tracker
and link it here.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1849615/comments/0

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On 2019-10-24T07:30:51+00:00 Gabriele Svelto wrote:

I filed a bug on Ubuntu's tracker. I've also dug a little bit further in
the crashes and this is not related to WebRTC per-se. The most visible
signatures are in WebRTC code but they're not the only ones. This is
caused by checks in libc that check if the file descriptor values passed
to the `FD_SET`, `FD_CLR` and `FD_ISSET` macros are less than the
`FD_SETSIZE` value. All code calling `select()` both directly and
indirectly seems to be affected. In WebRTC we're receiving file
descriptors from `inotify_init()`, is it possible that this will return
values larger than `FD_SETSIZE`?

Switching to `poll()` would probably fix the issue here but there's a
few things that are odd about this bug: for starters, why is it only
happening on Ubuntu/Debian and not on our builds? Also, this is
happening in code that calls `select()` outside of Firefox and those
crashes are also happening only on Ubuntu/Debian builds, not ours.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1849615/comments/3

------------------------------------------------------------------------
On 2019-10-24T08:13:44+00:00 Gabriele Svelto wrote:

I did some further digging and this is happening all over the place but
mostly in code we don't control. It's always `select()`'s fault though.
Daniel, this code is different from upstream WebRTC (which is also using
`select()` but in other places), is there a reason for this? I can cook
up a patch to switch this code to `poll()` instead but I wonder if it's
the right thing to do or if this should be fixed upstream first.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1849615/comments/5

** Changed in: firefox
       Status: Unknown => Confirmed

** Changed in: firefox
   Importance: Unknown => Critical

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  WebRTC-related crashes

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