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    Subject[PATCH 4.9 149/223] net: bridge: mcast: fix stale ipv6 hdr pointer when handling v6 query
    Date
    From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

    [ Upstream commit 3b26a5d03d35d8f732d75951218983c0f7f68dff ]

    We get a pointer to the ipv6 hdr in br_ip6_multicast_query but we may
    call pskb_may_pull afterwards and end up using a stale pointer.
    So use the header directly, it's just 1 place where it's needed.

    Fixes: 08b202b67264 ("bridge br_multicast: IPv6 MLD support.")
    Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
    Tested-by: Martin Weinelt <martin@linuxlounge.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/bridge/br_multicast.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    --- a/net/bridge/br_multicast.c
    +++ b/net/bridge/br_multicast.c
    @@ -1379,7 +1379,6 @@ static int br_ip6_multicast_query(struct
    struct sk_buff *skb,
    u16 vid)
    {
    - const struct ipv6hdr *ip6h = ipv6_hdr(skb);
    struct mld_msg *mld;
    struct net_bridge_mdb_entry *mp;
    struct mld2_query *mld2q;
    @@ -1423,7 +1422,7 @@ static int br_ip6_multicast_query(struct

    if (is_general_query) {
    saddr.proto = htons(ETH_P_IPV6);
    - saddr.u.ip6 = ip6h->saddr;
    + saddr.u.ip6 = ipv6_hdr(skb)->saddr;

    br_multicast_query_received(br, port, &br->ip6_other_query,
    &saddr, max_delay);

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