netdev - Re: TCP-MD5 checksum failure on x86

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: <1273147586.2357.63.camel@edumazet-laptop>
Date:	Thu, 06 May 2010 14:06:26 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Bhaskar Dutta <bhaskie@...il.com>
Cc:	Stephen Hemminger <shemminger@...tta.com>,
	Ben Hutchings <bhutchings@...arflare.com>,
	netdev@...r.kernel.org
Subject: Re: TCP-MD5 checksum failure on x86_64 SMP

Le jeudi 06 mai 2010 à 17:25 +0530, Bhaskar Dutta a écrit :

> I put in the above change and ran some load tests with around 50
> active TCP connections doing MD5.
> I could see only 1 bad packet in 30 min (earlier the problem used to
> occur instantaneously and repeatedly).
> 
> I think there is another possibility of being preempted when calling
> tcp_alloc_md5sig_pool()
> this function releases the spinlock when calling __tcp_alloc_md5sig_pool().
> 
> I will run some more tests after changing the  tcp_alloc_md5sig_pool
> and see if the problem is completely resolved.
> 

This code should be completely rewritten for linux-2.6.35, its very ugly
and over complex, yet it is not scalable.

It could use true percpu data, with no central lock or refcount.



--
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