Messages in this thread | | | Subject | Re: [PATCH net] bridge: mcast: Fix MLD2 Report IPv6 payload length check | From | Nikolay Aleksandrov <> | Date | Sun, 5 Jul 2020 22:11:39 +0300 |
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On 7/5/20 10:08 PM, Linus Lüssing wrote: > On Sun, Jul 05, 2020 at 09:33:13PM +0300, Nikolay Aleksandrov wrote: >> On 05/07/2020 21:22, Linus Lüssing wrote: >>> Commit e57f61858b7c ("net: bridge: mcast: fix stale nsrcs pointer in >>> igmp3/mld2 report handling") introduced a small bug which would potentially >>> lead to accepting an MLD2 Report with a broken IPv6 header payload length >>> field. >>> >>> The check needs to take into account the 2 bytes for the "Number of >>> Sources" field in the "Multicast Address Record" before reading it. >>> And not the size of a pointer to this field. >>> >>> Fixes: e57f61858b7c ("net: bridge: mcast: fix stale nsrcs pointer in igmp3/mld2 report handling") >>> Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> >>> --- >>> net/bridge/br_multicast.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >> >> I'd rather be more concerned with it rejecting a valid report due to wrong size. The ptr >> size would always be bigger. :) >> >> Thanks! >> Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> > > Aiy, you're right, it's the other way round. I'll update the > commit message and send a v2 in a minute, with your Acked-by > included. >
By the way, I can't verify at the moment, but I think we can drop that whole hunk altogether since skb_header_pointer() is used and it will simply return an error if there isn't enough data for nsrcs.
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