Re: kern/44418 (FAST_IPSEC and if_wm kernel panic - may affect the whole network stack)

[Wolfgang Stukenbrock <Wolfgang.Stukenbrock%nagler-company.com@localhost>]

The following reply was made to PR kern/44418; it has been noted by GNATS.

From: Wolfgang Stukenbrock <Wolfgang.Stukenbrock%nagler-company.com@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost, 
gnats-admin%NetBSD.org@localhost,
        drochner%NetBSD.org@localhost, 
Wolfgang.Stukenbrock%nagler-company.com@localhost
Subject: Re: kern/44418 (FAST_IPSEC and if_wm kernel panic - may affect the 
whole network stack)
Date: Fri, 11 Feb 2011 15:03:18 +0100

 Hi,
 
 I've had a look at it again and with the aproach to aquire the 
 KENREL_LOOK in ipsec_reinject_ipstack() this way of dooing it seems to 
 be OK.
 
 But I've just recognised another very small whole in this patch.
 (Also included in my original posting  - sorry)
 
 When the softnet_lock is aquired, the spl-level should have been already 
 raised to splnet/splsoftnet!
 Otherwise we may hold the lock and an Interrupt on splnet/splsoftnet 
 could be taken.
 In that interrupt we may try to lock the softnet_lock on the same CPU 
 again - resulting in panic ...
 This whole is of cause very small, so the change to stumble over it is 
 very very small.
 Same problem when freeing the lock again.
 
 The order of splx()/splsoftnet() and mutex_enter()/mutex_exit() should 
 be changed.
 
 If that is corrected too, I think the PR can be closed.
 
 Best regards.
 
 W. Stukenbrock
 
 drochner%NetBSD.org@localhost wrote:
 
 > Synopsis: FAST_IPSEC and if_wm kernel panic - may affect the whole network 
 > stack
 > 
 > State-Changed-From-To: open->feedback
 > State-Changed-By: drochner%NetBSD.org@localhost
 > State-Changed-When: Thu, 10 Feb 2011 21:28:08 +0000
 > State-Changed-Why:
 > added acquisition of softnet_lock as suggested in the PR, added
 > KERNEL_LOCK differently, only for ip_output.
 > For me, a dual-CPU box is solid.
 > 
 > 
 > 
 > 
 
 
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