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    Subject[PATCH 5.19 067/365] bpf: Acquire map uref in .init_seq_private for sock{map,hash} iterator
    Date
    From: Hou Tao <houtao1@huawei.com>

    commit f0d2b2716d71778d0b0c8eaa433c073287d69d93 upstream.

    sock_map_iter_attach_target() acquires a map uref, and the uref may be
    released before or in the middle of iterating map elements. For example,
    the uref could be released in sock_map_iter_detach_target() as part of
    bpf_link_release(), or could be released in bpf_map_put_with_uref() as
    part of bpf_map_release().

    Fixing it by acquiring an extra map uref in .init_seq_private and
    releasing it in .fini_seq_private.

    Fixes: 0365351524d7 ("net: Allow iterating sockmap and sockhash")
    Signed-off-by: Hou Tao <houtao1@huawei.com>
    Acked-by: Yonghong Song <yhs@fb.com>
    Link: https://lore.kernel.org/r/20220810080538.1845898-5-houtao@huaweicloud.com
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/core/sock_map.c | 20 +++++++++++++++++++-
    1 file changed, 19 insertions(+), 1 deletion(-)

    --- a/net/core/sock_map.c
    +++ b/net/core/sock_map.c
    @@ -783,13 +783,22 @@ static int sock_map_init_seq_private(voi
    {
    struct sock_map_seq_info *info = priv_data;

    + bpf_map_inc_with_uref(aux->map);
    info->map = aux->map;
    return 0;
    }

    +static void sock_map_fini_seq_private(void *priv_data)
    +{
    + struct sock_map_seq_info *info = priv_data;
    +
    + bpf_map_put_with_uref(info->map);
    +}
    +
    static const struct bpf_iter_seq_info sock_map_iter_seq_info = {
    .seq_ops = &sock_map_seq_ops,
    .init_seq_private = sock_map_init_seq_private,
    + .fini_seq_private = sock_map_fini_seq_private,
    .seq_priv_size = sizeof(struct sock_map_seq_info),
    };

    @@ -1369,18 +1378,27 @@ static const struct seq_operations sock_
    };

    static int sock_hash_init_seq_private(void *priv_data,
    - struct bpf_iter_aux_info *aux)
    + struct bpf_iter_aux_info *aux)
    {
    struct sock_hash_seq_info *info = priv_data;

    + bpf_map_inc_with_uref(aux->map);
    info->map = aux->map;
    info->htab = container_of(aux->map, struct bpf_shtab, map);
    return 0;
    }

    +static void sock_hash_fini_seq_private(void *priv_data)
    +{
    + struct sock_hash_seq_info *info = priv_data;
    +
    + bpf_map_put_with_uref(info->map);
    +}
    +
    static const struct bpf_iter_seq_info sock_hash_iter_seq_info = {
    .seq_ops = &sock_hash_seq_ops,
    .init_seq_private = sock_hash_init_seq_private,
    + .fini_seq_private = sock_hash_fini_seq_private,
    .seq_priv_size = sizeof(struct sock_hash_seq_info),
    };


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