netdev - Re: [PATCH] net: fix problem in dequeuing from input_pkt

lists.openwall.net		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 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1274330246.2658.16.camel@edumazet-laptop>
Date:	Thu, 20 May 2010 06:37:26 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Tom Herbert <therbert@...gle.com>
Cc:	Changli Gao <xiaosuo@...il.com>, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH] net: fix problem in dequeuing from input_pkt_queue

Le mercredi 19 mai 2010 à 19:48 -0700, Tom Herbert a écrit :
> >> It should be okay?  process_backlog only runs in softirq so bottom
> >> halves are already disabled, and I don't think flush_backlog runs out
> >> of an interrupt.
> >>
> >
> > Oh no. It is an IRQ handler.
> >
> Very well, I will fix that.
> 
> Now I'm wondering, though, what the purpose of flush_backlog is...
> since __netif_receive_skb is called with interrupts enabled it's
> obvious flush_backlog won't catch all the skb's that reference the
> device go away.  Is there a reason these packets need to be flushed
> and can't just be processed?

flush_backlog is called when device is dismantled.

No new packets should be generated by the device at this moment.

Could you please split your patch in units, I spent 20 minutes to review
it and come to same conclusion than Changli (need to disable interrupts
as they are currently disabled) and also :

input_queue_head_incr(sd); are _not_ needed in flush_backlog()

We are in the very last moments of the life of the device, in a very
unlikely situation (packets in flight, not already consumed by the cpu),
we are _dropping_ packets, so OOO means nothing at this point. 

In dev_cpu_callback(), you reverse the order of input_pkt_queue /
process_queue.

Thats fine, but should be a single patch, because I am not sure the
input_queue_head_incr() are valid here, since we re-inject these packets
to netif_rx(). Could you clarify this point ?

Thanks !


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html