filt_timerexpire: do not iterate over the interval
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Authored by kib on May 1 2021, 3:08 PM.

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rG7cb40543e964: filt_timerexpire: do not iterate over the interval

Summary

User-supplied data might make this loop too time-consuming. Divide directly, and handle both the possibility that we were woken up earlier, and arithmetic overflows/underflows from the calculation.

Reported by: pho

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rG FreeBSD src repository

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kib requested review of this revision.May 1 2021, 3:08 PM

kib created this revision.

markj added inline comments.May 3 2021, 1:38 PM

sys/kern/kern_event.c
742	This case represents the timer firing early - why do we adjust anything here?

kib marked an inline comment as done.May 3 2021, 3:37 PM

kib added inline comments.

sys/kern/kern_event.c
742	Because it is activating knote, which was done before too.

markj accepted this revision.May 3 2021, 3:59 PM

This revision is now accepted and ready to land.May 3 2021, 3:59 PM

Skip activation for the case now <= kc_next, and do not increment data.

This revision now requires review to proceed.May 3 2021, 4:03 PM

markj accepted this revision.May 3 2021, 4:16 PM

This revision is now accepted and ready to land.May 3 2021, 4:16 PM

Closed by commit rG7cb40543e964: filt_timerexpire: do not iterate over the interval (authored by kib). · Explain WhyMay 3 2021, 4:51 PM

This revision was automatically updated to reflect the committed changes.

kib added a commit: rG7cb40543e964: filt_timerexpire: do not iterate over the interval.

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sys/

kern/

kern_event.c

15 lines

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filt_timerexpire: do not iterate over the intervalClosedPublicActions