On Mon, 2012-12-10 at 13:41 -0500, David Miller wrote: > From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> > Date: Mon, 10 Dec 2012 10:41:06 +0100 > > > From: Johannes Berg <johannes.berg@xxxxxxxxx> > > > > ip_check_defrag() might be called from af_packet within the > > RX path where shared SKBs are used, so it must not modify > > the input SKB before it has unshared it for defragmentation. > > Use skb_copy_bits() to get the IP header and only pull in > > everything later. > > > > The same is true for the other caller in macvlan as it is > > called from dev->rx_handler which can also get a shared SKB. > > > > Reported-by: Eric Leblond <eric@xxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> > > --- > > For some versions of the kernel, this code goes into af_packet.c > > So the bug is that ip_check_defrag() has a precondition which is met > properly by all callers except AF_PACKET. > > If this is the case, remind me why are we changing ip_check_defrag() > rather than the violator of the precondition? I don't think this is the case. If you're referring to my note about af_packet: the kernels where this goes into af_packet.c are the kernels that don't even have ip_check_defrag() because macvlan didn't exist/didn't have ip defrag support and af_packet had this code there -- see commit bc416d9768a. If you're not referring to my note about af_packet: both callers (there are only two) of ip_check_defrag() have this bug as far as I can tell because they're both in the part of the RX path where shared SKBs might happen. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
