netdev - NET_DMA: where do we ever call dma_skb_copy_datagram_iovec() with NULL pinned

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: <20070721034829.GL21668@ftp.linux.org.uk>
Date:	Sat, 21 Jul 2007 04:48:29 +0100
From:	Al Viro <viro@....linux.org.uk>
To:	netdev@...r.kernel.org
Cc:	christopher.leech@...el.com
Subject: NET_DMA: where do we ever call dma_skb_copy_datagram_iovec() with NULL pinned_list?

	AFAICS, all callers of dma_skb_copy_datagram_iovec()
are either
	* recursive for fragments, pass pinned_list unchanged or
	* called from tcp, with pinned_list coming from
tp->ucopy.pinned_list and only when tp->ucopy.dma_chan is non-NULL.

Now, all non-NULL assignments to ->dma_chan have the same form:
	if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
		tp->ucopy.dma_chan = get_softnet_dma();
IOW, if ->ucopy.pinned_list stays NULL, ->ucopy.dma_chan will do the same.

Moreover, any place that resets ->ucopy.pinned_list will also reset
->ucopy.dma_chan.

IOW, we can't ever get non-NULL tp->ucopy.dma_chan while tp->ucopy.pinned_list
is NULL.  So how can we ever get to the dma_memcpy_to_kernel_iovec()?
-
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