CVS commit: src/sys/net

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Tue Mar 15 00:05:18 UTC 2022

Modified Files:
        src/sys/net: if_tun.c

Log Message:
tun(4): Fix bug introduced in previous locking change.

Now that tun_lock runs at IPL_NONE, taking it does not have the side
effect of disabling preemption, but pktq_enqueue assumes the caller
has disabled preemption so it can safely schedule a softint.

This isn't a problem in most physical network drivers because the
pktq_enqueue call happens from within the driver's softint context
anyway.  But tun(4) is special -- here, the pktq_enqueue is triggered
by a userland write to the device, which is in thread context.  So
let's just disable preemption in tunwrite.

Reported-by: syzbot+21c2cb300f1ec2162b35%syzkaller.appspotmail.com@localhost


To generate a diff of this commit:
cvs rdiff -u -r1.171 -r1.172 src/sys/net/if_tun.c

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