SYZFAIL: open of /dev/kcov failed

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0930b1039b64 Dump more data in the hopes of figuring out w..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=145c50e1b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=bf87b6915a88cd0d
dashboard link: https://syzkaller.appspot.com/bug?extid=17e0e39fd4ed1eeca4d2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17e0e3...@syzkaller.appspotmail.com

SYZFAIL: open of /dev/kcov failed
(errno 13: Permission denied)
SYZFAIL: child failed
(errno 0: Undefined error: 0)
loop exited with status 67


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[Aleksandr Nogikh]

This is apparently due to https://github.com/google/syzkaller/pull/2882
Now only 3 kcov instances are instantiated at syz-executor's startup
and the others only when needed. It seems that it'd be more
sandboxing-friendly to create kcov instances for all threads at the
very beginning, but don't mmap them until they're needed.

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[syzbot]

> Hey Anton,
>
> This is probably a transient condition that Alexandr already worked around
> in https://github.com/google/syzkaller/pull/2904
> <https://www.google.com/url?q=https://github.com/google/syzkaller/pull/2904&sa=D&source=hangouts&ust=1638738950466000&usg=AOvVaw1hfow-2eaXP2RMKw9-n3Cg>.
> He said the problem was due to trying to open the kcov(4) device from a
> child process. Do you recall why we have this restriction? It's not spelled
> out in the man page AFAICT.
>
> Thanks
> Greg
>
> #syz invalid

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>
> On Fri, Dec 3, 2021 at 3:51 AM syzbot <

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