CVS commit: src/sys/kern

["Kamil Rytarowski" <kamil%netbsd.org@localhost>]

Module Name:    src
Committed By:   kamil
Date:           Sun Jul  8 14:42:52 UTC 2018

Modified Files:
        src/sys/kern: kern_timeout.c

Log Message:
Try to avoid signed integer overflow in callout_softclock()

The delta operation (c->c_time - ticks) is documented as safe, however it
still can cause overflow in narrow case scenarios.

Try to avoid overflow/underflow or at least make it less frequent with
a direct comparison of c->c_time and tics. Perform the operation of
subtraction only when c->c_time > ticks.

sys/kern/kern_timeout.c:720:9, signed integer overflow: -2147410738 - 72912 cannot be represented in type 'int'

Detected with Kernel Undefined Behavior Sanitizer.

Patch suggested by <Riastradh>


To generate a diff of this commit:
cvs rdiff -u -r1.54 -r1.55 src/sys/kern/kern_timeout.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.