netdev - Re: [RFC PATCH] af_packet: don't to defrag shared skb

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Message-ID: <1354916502.9124.18.camel@jlt4.sipsolutions.net>
Date:	Fri, 07 Dec 2012 22:41:42 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	David Miller <davem@...emloft.net>
Cc:	eric@...it.org, netdev@...r.kernel.org,
	linux-wireless@...r.kernel.org, linville@...driver.com
Subject: Re: [RFC PATCH] af_packet: don't to defrag shared skb

On Fri, 2012-12-07 at 22:30 +0100, Johannes Berg wrote:

> The only other theory I can come up with right now is that the skb_get()
> happens in deliver_skb via __netif_receive_skb. Keeping in mind that
> wpa_supplicant might have another packet socket open for authentication
> packets, that seems like a possibility. I'll test it once I figure out
> how to do this "defrag" option you speak of :)

Hmm now I'm venturing into the unknown (for me) and realm of
speculation...

wpa_supplicant opens a packet socket for ETH_P_EAPOL, which indirectly
eventually calls dev_add_pack(). But if you do the same for another
socket, you'll get the same again, and then deliver_skb() will deliver
only a refcounted packet to the prot_hook->func().

This seems like it could very well cause the problem?

johannes

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