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    Subject[PATCH 5.19 189/365] netfilter: nf_tables: use READ_ONCE and WRITE_ONCE for shared generation id access
    Date
    From: Pablo Neira Ayuso <pablo@netfilter.org>

    commit 3400278328285a8c2f121904496aff5e7b610a01 upstream.

    The generation ID is bumped from the commit path while holding the
    mutex, however, netlink dump operations rely on RCU.

    This patch also adds missing cb->base_eq initialization in
    nf_tables_dump_set().

    Fixes: 38e029f14a97 ("netfilter: nf_tables: set NLM_F_DUMP_INTR if netlink dumping is stale")
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/netfilter/nf_tables_api.c | 20 +++++++++++++-------
    1 file changed, 13 insertions(+), 7 deletions(-)

    --- a/net/netfilter/nf_tables_api.c
    +++ b/net/netfilter/nf_tables_api.c
    @@ -889,7 +889,7 @@ static int nf_tables_dump_tables(struct

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (family != NFPROTO_UNSPEC && family != table->family)
    @@ -1705,7 +1705,7 @@ static int nf_tables_dump_chains(struct

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (family != NFPROTO_UNSPEC && family != table->family)
    @@ -3149,7 +3149,7 @@ static int nf_tables_dump_rules(struct s

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (family != NFPROTO_UNSPEC && family != table->family)
    @@ -4133,7 +4133,7 @@ static int nf_tables_dump_sets(struct sk

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (ctx->family != NFPROTO_UNSPEC &&
    @@ -5061,6 +5061,8 @@ static int nf_tables_dump_set(struct sk_

    rcu_read_lock();
    nft_net = nft_pernet(net);
    + cb->seq = READ_ONCE(nft_net->base_seq);
    +
    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (dump_ctx->ctx.family != NFPROTO_UNSPEC &&
    dump_ctx->ctx.family != table->family)
    @@ -6887,7 +6889,7 @@ static int nf_tables_dump_obj(struct sk_

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (family != NFPROTO_UNSPEC && family != table->family)
    @@ -7819,7 +7821,7 @@ static int nf_tables_dump_flowtable(stru

    rcu_read_lock();
    nft_net = nft_pernet(net);
    - cb->seq = nft_net->base_seq;
    + cb->seq = READ_ONCE(nft_net->base_seq);

    list_for_each_entry_rcu(table, &nft_net->tables, list) {
    if (family != NFPROTO_UNSPEC && family != table->family)
    @@ -8752,6 +8754,7 @@ static int nf_tables_commit(struct net *
    struct nft_trans_elem *te;
    struct nft_chain *chain;
    struct nft_table *table;
    + unsigned int base_seq;
    LIST_HEAD(adl);
    int err;

    @@ -8801,9 +8804,12 @@ static int nf_tables_commit(struct net *
    * Bump generation counter, invalidate any dump in progress.
    * Cannot fail after this point.
    */
    - while (++nft_net->base_seq == 0)
    + base_seq = READ_ONCE(nft_net->base_seq);
    + while (++base_seq == 0)
    ;

    + WRITE_ONCE(nft_net->base_seq, base_seq);
    +
    /* step 3. Start new generation, rules_gen_X now in use. */
    net->nft.gencursor = nft_gencursor_next(net);


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