GPF when doing jail -r, possibly an use-after-free

[Mikolaj Golub]

On Thu, 5 Jul 2012 20:21:53 +0000 Bjoern A. Zeeb wrote:

 BAZ> On 5. Jul 2012, at 19:53 , Mikolaj Golub wrote:

 >> 
 >> On Thu, 05 Jul 2012 12:18:20 -0700 Xin Li wrote:
 >> 
 >> XL> Hi, Mikolaj,
 >> 
 >> XL> On 07/04/12 00:00, Mikolaj Golub wrote:
 >>>> Is this observed after destroying epair? There is an issue with
 >>>> epair: on destroy, when epair_clone_destroy() calls
 >>>> ether_ifdetach() for its second half it does not switch to its vnet
 >>>> and if_detach_internal() can't find the interface and just returns.
 >>>> As a result V_ifnet list is left with dead reference.
 >> 
 >> XL> Yes.
 >> 
 >>>> http://lists.freebsd.org/pipermail/freebsd-virtualization/2011-January/000628.html
 >>>> 
 >>>> Here is an updated patch against CURRENT:
 >>>> 
 >>>> http://people.freebsd.org/~trociny/if_epair.c.epair_clone_destroy.1.patch
 >> 
 >> XL> Your
 >>>> 
 >> XL> patch did fixed the problem, thanks!  Are you going to commit it
 >> XL> against -HEAD and then MFC after a while?
 >> 
 >> I would like Bjoern review it before me committing, or at least tell he does
 >> not mind, if he does not have time to review -)

 BAZ> To me the patch looks wrong; I am wondering if someone broke some other central
 BAZ> assumptions but given I cannot currently spend time on this and if it fixes things
 BAZ> feel free to go ahead.

If you told what looks wrong I could try to dig at that direction and might be
back with a better solution, instead of committing a presumably wrong fix.

-- 
Mikolaj Golub