On Wednesday, September 28, 2016 7:20:39 PM CEST Jay Smith wrote: > Actually, on a little more searching of this list's archives, I think > that this discussion: https://patchwork.kernel.org/patch/9260733/ is > about exactly the same issue I've found, except from the TCP side. I'm > cc'ing a few of the participants from that discussion. > > So is the patch proposed there (copying and restoring the entire > iov_iter in skb_copy_and_csum_datagram_msg()) being considered as a > fix?
>From Alan's post: "My ugly patch fixes this in the most obvious way: make a local copy of msg->msg_iter before the call to skb_copy_and_csum_datagram(), and copy it back if the checksum is bad, just before goto csum_error;" IMHO this meant that the patch is a proof of concept for his problem. > If not, would an alternate one that concealed the save-and-restore logic > inside iov_iter.c be more acceptable? I'd be happy to produce whatever's > needed, or yield to someone with stronger feelings about where it should > go... Al Viro identified more inconsistencies within the error-paths that deal with EFAULT in the whole area (in and around skb_copy_and_csum_datagram()). As far as I can tell the original discussion about the data corruption issue went off on a tangent and it is stuck in figuring out "How to handle the errors in tcp_copy_to_iovec()". As for fixing the issue: I'm happy to test and review patches. The trouble is that nobody seem to be able to produce them... Regards, Christian
