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    Subject[PATCH 3.16 165/245] netfilter: ipset: avoid null deref when IPSET_ATTR_LINENO is present
    3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

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

    From: Florian Westphal <fw@strlen.de>

    commit 22dad713b8a5ff488e07b821195270672f486eb2 upstream.

    The set uadt functions assume lineno is never NULL, but it is in
    case of ip_set_utest().

    syzkaller managed to generate a netlink message that calls this with
    LINENO attr present:

    general protection fault: 0000 [#1] PREEMPT SMP KASAN
    RIP: 0010:hash_mac4_uadt+0x1bc/0x470 net/netfilter/ipset/ip_set_hash_mac.c:104
    Call Trace:
    ip_set_utest+0x55b/0x890 net/netfilter/ipset/ip_set_core.c:1867
    nfnetlink_rcv_msg+0xcf2/0xfb0 net/netfilter/nfnetlink.c:229
    netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
    nfnetlink_rcv+0x1ba/0x460 net/netfilter/nfnetlink.c:563

    pass a dummy lineno storage, its easier than patching all set
    implementations.

    This seems to be a day-0 bug.

    Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
    Reported-by: syzbot+34bd2369d38707f3f4a7@syzkaller.appspotmail.com
    Fixes: a7b4f989a6294 ("netfilter: ipset: IP set core support")
    Signed-off-by: Florian Westphal <fw@strlen.de>
    Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    [bwh: Backported to 3.16: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    net/netfilter/ipset/ip_set_core.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/net/netfilter/ipset/ip_set_core.c
    +++ b/net/netfilter/ipset/ip_set_core.c
    @@ -1549,6 +1549,7 @@ ip_set_utest(struct sock *ctnl, struct s
    struct ip_set *set;
    struct nlattr *tb[IPSET_ATTR_ADT_MAX+1] = {};
    int ret = 0;
    + u32 lineno;

    if (unlikely(protocol_failed(attr) ||
    attr[IPSET_ATTR_SETNAME] == NULL ||
    @@ -1565,7 +1566,7 @@ ip_set_utest(struct sock *ctnl, struct s
    return -IPSET_ERR_PROTOCOL;

    read_lock_bh(&set->lock);
    - ret = set->variant->uadt(set, tb, IPSET_TEST, NULL, 0, 0);
    + ret = set->variant->uadt(set, tb, IPSET_TEST, &lineno, 0, 0);
    read_unlock_bh(&set->lock);
    /* Userspace can't trigger element to be re-added */
    if (ret == -EAGAIN)
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