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    Subject[PATCH 4.4 198/312] netfilter: nft_dynset: fix panic if NFT_SET_HASH is not enabled
    Date
    From: Liping Zhang <zlpnobody@gmail.com>

    commit bb6a6e8e091353770074608c1d1bfde0e20b8154 upstream.

    When CONFIG_NFT_SET_HASH is not enabled and I input the following rule:
    "nft add rule filter output flow table test {ip daddr counter }", kernel
    panic happened on my system:
    BUG: unable to handle kernel NULL pointer dereference at (null)
    IP: [< (null)>] (null)
    [...]
    Call Trace:
    [<ffffffffa0590466>] ? nft_dynset_eval+0x56/0x100 [nf_tables]
    [<ffffffffa05851bb>] nft_do_chain+0xfb/0x4e0 [nf_tables]
    [<ffffffffa0432f01>] ? nf_conntrack_tuple_taken+0x61/0x210 [nf_conntrack]
    [<ffffffffa0459ea6>] ? get_unique_tuple+0x136/0x560 [nf_nat]
    [<ffffffffa043bca1>] ? __nf_ct_ext_add_length+0x111/0x130 [nf_conntrack]
    [<ffffffffa045a357>] ? nf_nat_setup_info+0x87/0x3b0 [nf_nat]
    [<ffffffff81761e27>] ? ipt_do_table+0x327/0x610
    [<ffffffffa045a6d7>] ? __nf_nat_alloc_null_binding+0x57/0x80 [nf_nat]
    [<ffffffffa059f21f>] nft_ipv4_output+0xaf/0xd0 [nf_tables_ipv4]
    [<ffffffff81702515>] nf_iterate+0x55/0x60
    [<ffffffff81702593>] nf_hook_slow+0x73/0xd0

    Because in rbtree type set, ops->update is not implemented. So just keep
    it simple, in such case, report -EOPNOTSUPP to the user space.

    Fixes: 22fe54d5fefc ("netfilter: nf_tables: add support for dynamic set updates")
    Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/netfilter/nft_dynset.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/net/netfilter/nft_dynset.c
    +++ b/net/netfilter/nft_dynset.c
    @@ -121,6 +121,9 @@ static int nft_dynset_init(const struct
    return PTR_ERR(set);
    }

    + if (set->ops->update == NULL)
    + return -EOPNOTSUPP;
    +
    if (set->flags & NFT_SET_CONSTANT)
    return -EBUSY;


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