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    Subject[PATCH 4.14 02/23] net: fix IPv6 prefix route residue
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ Upstream commit e75913c93f7cd5f338ab373c34c93a655bd309cb ]

    Follow those steps:
    # ip addr add 2001:123::1/32 dev eth0
    # ip addr add 2001:123:456::2/64 dev eth0
    # ip addr del 2001:123::1/32 dev eth0
    # ip addr del 2001:123:456::2/64 dev eth0
    and then prefix route of 2001:123::1/32 will still exist.

    This is because ipv6_prefix_equal in check_cleanup_prefix_route
    func does not check whether two IPv6 addresses have the same
    prefix length. If the prefix of one address starts with another
    shorter address prefix, even though their prefix lengths are
    different, the return value of ipv6_prefix_equal is true.

    Here I add a check of whether two addresses have the same prefix
    to decide whether their prefixes are equal.

    Fixes: 5b84efecb7d9 ("ipv6 addrconf: don't cleanup prefix route for IFA_F_NOPREFIXROUTE")
    Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
    Reported-by: Wenhao Zhang <zhangwenhao8@huawei.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/ipv6/addrconf.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
    index 9ac6f62322946..c47161e92407b 100644
    --- a/net/ipv6/addrconf.c
    +++ b/net/ipv6/addrconf.c
    @@ -1124,7 +1124,8 @@ check_cleanup_prefix_route(struct inet6_ifaddr *ifp, unsigned long *expires)
    list_for_each_entry(ifa, &idev->addr_list, if_list) {
    if (ifa == ifp)
    continue;
    - if (!ipv6_prefix_equal(&ifa->addr, &ifp->addr,
    + if (ifa->prefix_len != ifp->prefix_len ||
    + !ipv6_prefix_equal(&ifa->addr, &ifp->addr,
    ifp->prefix_len))
    continue;
    if (ifa->flags & (IFA_F_PERMANENT | IFA_F_NOPREFIXROUTE))
    --
    2.19.1


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