Differential D30233

posix timers: Check for overflow when converting to ns
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Authored by markj on May 12 2021, 4:48 PM.

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rGec00c33f8181: posix timers: Check for overflow when converting to ns
rG8b3c4231abf0: posix timers: Check for overflow when converting to ns

Summary

Disallow a time or timer period value when the conversion to nanoseconds
would overflow. Otherwise it is possible to trigger a divison by zero
in realtime_expire_l(), where we compute the number of overruns by
dividing by the interval.

Fixes: 7995dae9 ("posix timers: Improve the overrun calculation")
Reported by: syzbot+5ab360bd3d3e3c5a6e0e@syzkaller.appspotmail.com
Reported by: syzbot+157b74ff493140d86eac@syzkaller.appspotmail.com
MFC after: 1 week

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rS FreeBSD src repository - subversion

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Buildable 39147
Build 36036: arc lint + arc unit

Event Timeline

markj created this revision.May 12 2021, 4:48 PM

Herald added a subscriber: imp. · View Herald TranscriptMay 12 2021, 4:48 PM

markj requested review of this revision.May 12 2021, 4:48 PM

Harbormaster completed remote builds in B39142: Diff 89081.May 12 2021, 4:48 PM

I think we want some symbol like ONE_SEC_NS, so that reader can be freed from counting zeroes in the constant.

This revision is now accepted and ready to land.May 12 2021, 7:13 PM

Add NSEC_PER_SEC, use it throughout kern_time.c.

This revision now requires review to proceed.May 12 2021, 8:59 PM

Harbormaster completed remote builds in B39147: Diff 89092.May 12 2021, 8:59 PM

kib accepted this revision.May 12 2021, 10:29 PM

kib added inline comments.

sys/kern/kern_time.c
75	The 'L' suffix is not needed, I believe.

This revision is now accepted and ready to land.May 12 2021, 10:29 PM

Closed by commit rG8b3c4231abf0: posix timers: Check for overflow when converting to ns (authored by markj). · Explain WhyMay 13 2021, 12:35 PM

This revision was automatically updated to reflect the committed changes.

markj added a commit: rG8b3c4231abf0: posix timers: Check for overflow when converting to ns.

markj added a commit: rGec00c33f8181: posix timers: Check for overflow when converting to ns.May 20 2021, 2:11 PM

Revision Contents
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sys/

kern/

21 lines

Diff 89092

sys/kern/kern_time.c

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