kern/73719: Page fault in bpf_mtap ()
wawa at yandex-team.ru
Tue Nov 9 12:10:31 PST 2004
The following reply was made to PR kern/73719; it has been noted by GNATS.
From: Vladimir Ivanov <wawa at yandex-team.ru>
To: freebsd-gnats-submit at FreeBSD.org, wawa at yandex-team.ru
Subject: Re: kern/73719: Page fault in bpf_mtap ()
Date: Tue, 09 Nov 2004 23:02:26 +0300
The bpf_mtap () seems to be little enough to make a look.
We suppose that most probable reason to panic is zero value of "bp" pointer.
Also, I know that bpf open/close are frequent on my system.
We can see (look at BPF_MTAP definition) that the value may be changed
from another thread after verification but before bpf_mtap call because
"ifp" points to global variable. The patch does not change the logic of
program as you can see but garantee "bp" is not NULL. The only side
effect is hypotetic pushing extra packet to just detached bpf device.
It's not very big price I seem
I've commited the patch to the system and awaiting results.
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