netdev - Question about skb

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <87fvo71a0m.fsf@natisbad.org>
Date:	Wed, 29 Jan 2014 09:12:57 +0100
From:	arno@...isbad.org (Arnaud Ebalard)
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	David Miller <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Willy Tarreau <w@....eu>,
	netdev@...r.kernel.org
Subject: Question about skb_segment()

Hi Herbert,

I wonder if you could share some knowledge on the behaviour of
skb_segment() as it is implemented in 3.13.0: when passed a GSO
packet to be segmented, can the skb result have skb->next == NULL?

One would expect the number of segments of the result to usually match
tcp_skb_pcount() of passed packet and hence having skb->next != NULL: 
AFAICT, this what usually happens when skb_segment() is called in
tcp_gso_segment() but I noticed some cases where the number of segments
(length of chained sk_buff) is lower than the expected value and also
have two backtraces resulting from a skb delivered with a NULL skb->next. 

The whole thread leading to my question is here, in case you want to
take a look:

 http://thread.gmane.org/gmane.linux.network/301587

Thanks in advance,

a+
--
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