lkml.org 
[lkml]   [2018]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.18 086/171] netfilter: conntrack: fix calculation of next bucket number in early_drop
    Date
    4.18-stable review patch.  If anyone has any objections, please let me know.

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

    From: Vasily Khoruzhick <vasilykh@arista.com>

    commit f393808dc64149ccd0e5a8427505ba2974a59854 upstream.

    If there's no entry to drop in bucket that corresponds to the hash,
    early_drop() should look for it in other buckets. But since it increments
    hash instead of bucket number, it actually looks in the same bucket 8
    times: hsize is 16k by default (14 bits) and hash is 32-bit value, so
    reciprocal_scale(hash, hsize) returns the same value for hash..hash+7 in
    most cases.

    Fix it by increasing bucket number instead of hash and rename _hash
    to bucket to avoid future confusion.

    Fixes: 3e86638e9a0b ("netfilter: conntrack: consider ct netns in early_drop logic")
    Cc: <stable@vger.kernel.org> # v4.7+
    Signed-off-by: Vasily Khoruzhick <vasilykh@arista.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/netfilter/nf_conntrack_core.c | 13 ++++++++-----
    1 file changed, 8 insertions(+), 5 deletions(-)

    --- a/net/netfilter/nf_conntrack_core.c
    +++ b/net/netfilter/nf_conntrack_core.c
    @@ -929,19 +929,22 @@ static unsigned int early_drop_list(stru
    return drops;
    }

    -static noinline int early_drop(struct net *net, unsigned int _hash)
    +static noinline int early_drop(struct net *net, unsigned int hash)
    {
    - unsigned int i;
    + unsigned int i, bucket;

    for (i = 0; i < NF_CT_EVICTION_RANGE; i++) {
    struct hlist_nulls_head *ct_hash;
    - unsigned int hash, hsize, drops;
    + unsigned int hsize, drops;

    rcu_read_lock();
    nf_conntrack_get_ht(&ct_hash, &hsize);
    - hash = reciprocal_scale(_hash++, hsize);
    + if (!i)
    + bucket = reciprocal_scale(hash, hsize);
    + else
    + bucket = (bucket + 1) % hsize;

    - drops = early_drop_list(net, &ct_hash[hash]);
    + drops = early_drop_list(net, &ct_hash[bucket]);
    rcu_read_unlock();

    if (drops) {

    \
     
     \ /
      Last update: 2018-11-19 18:50    [W:3.283 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site