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    Subject[PATCH 5.10 56/99] net/packet: rx_owner_map depends on pg_vec
    Date
    From: Willem de Bruijn <willemb@google.com>

    [ Upstream commit ec6af094ea28f0f2dda1a6a33b14cd57e36a9755 ]

    Packet sockets may switch ring versions. Avoid misinterpreting state
    between versions, whose fields share a union. rx_owner_map is only
    allocated with a packet ring (pg_vec) and both are swapped together.
    If pg_vec is NULL, meaning no packet ring was allocated, then neither
    was rx_owner_map. And the field may be old state from a tpacket_v3.

    Fixes: 61fad6816fc1 ("net/packet: tpacket_rcv: avoid a producer race condition")
    Reported-by: Syzbot <syzbot+1ac0994a0a0c55151121@syzkaller.appspotmail.com>
    Signed-off-by: Willem de Bruijn <willemb@google.com>
    Reviewed-by: Eric Dumazet <edumazet@google.com>
    Link: https://lore.kernel.org/r/20211215143937.106178-1-willemdebruijn.kernel@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/packet/af_packet.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
    index 08144559eed56..f78097aa403a8 100644
    --- a/net/packet/af_packet.c
    +++ b/net/packet/af_packet.c
    @@ -4461,9 +4461,10 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
    }

    out_free_pg_vec:
    - bitmap_free(rx_owner_map);
    - if (pg_vec)
    + if (pg_vec) {
    + bitmap_free(rx_owner_map);
    free_pg_vec(pg_vec, order, req->tp_block_nr);
    + }
    out:
    return err;
    }
    --
    2.33.0


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