Module Name: src
Committed By: martin
Date: Wed Aug 15 12:07:30 UTC 2018
Modified Files:
src/sys/net [netbsd-8]: if_tun.c
Log Message:
Pull up following revision(s) (requested by ozaki-r in ticket #974):
sys/net/if_tun.c: revision 1.145
sys/net/if_tun.c: revision 1.146
tun: fix locking against myself
filt_tunread is called with tun_lock held from tun_output (via tun_output =>
selnotify => knote), so we must not take tun_lock in filt_tunread. The bug
is triggered only if a tun is used through kqueue.
Found by k-goda@IIJ
Fix tun(4) kevent locking
filt_tunread gets called in two contexts:
- by calls to selnotify in if_tun.c (or knote, as the case may be,
but not here), in which case tp->tun_lock is held; and
- by internal logic in kevent, in which tp->tun_lock is not held.
The standard convention to discriminate between these two cases is by
setting the kernel-only NOTE_SUBMIT bit in the hint to selnotify or
knote; then in filt_*:
if (hint & NOTE_SUBMIT)
KASSERT(mutex_owned(&tp->tun_lock));
else
mutex_enter(&tp->tun_lock);
...
if (hint & NOTE_SUBMIT)
KASSERT(mutex_owned(&tp->tun_lock));
else
mutex_exit(&tp->tun_lock);
Pointed out by and patch from riastradh@
Tested by ozaki-r@ (only the former path)
To generate a diff of this commit:
cvs rdiff -u -r1.139.2.3 -r1.139.2.4 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.
