lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date:	Fri, 27 Sep 2013 16:28:01 -0700
From:	Salam Noureddine <>
To:	Alexey Kuznetsov <>
Cc:	Stephen Hemminger <>,
	"David S. Miller" <>,
	James Morris <>,
	Hideaki YOSHIFUJI <>,
	Patrick McHardy <>,
Subject: Re: [PATCH 2/2] ipv4 igmp: use del_timer_sync instead of del_timer in ip_mc_down

Thanks for the explanation. Currenlty, __in_dev_put is both used in
timer handler function and in ip_mc_down where del_timer is invoked. I
guess we need to change the timer handler so it uses in_dev_put to do
proper cleanup in cases where it runs past the call to ip_mc_down and
has the last reference.

On Fri, Sep 27, 2013 at 4:15 PM, Alexey Kuznetsov <> wrote:
> On Fri, Sep 27, 2013 at 04:04:00PM -0700, Salam Noureddine wrote:
>>                               I don't quite understand the reason
>> for having __in_dev_put decrement the refcnt without destroying the
>> in_device in case it reaches 0. If the timer handler assumes it cannot
>> be the last one to hold a reference then that would mean it doesn't
>> need the reference in the first place.
> I would like to explain this, because this can result in a big mistake.
> Timer takes reference, when it _can_ be the last sometimes.
> When we do del_timer() and know for sure that someone holds refcnt, we can just
> decrese it. In this cae it is obvious: we sit in context whcih deals with in_dev,
> so that reference from timer acannot be the last: caller of the function holds refcnt.
> But in another places timer _expires_ and that last reference is dropped by in_dev_put().
> Alexey
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists