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    Subject[PATCH 5.10 531/545] mac80211: fix a memory leak where sta_info is not freed
    Date
    From: Ahmed Zaki <anzaki@gmail.com>

    commit 8f9dcc29566626f683843ccac6113a12208315ca upstream.

    The following is from a system that went OOM due to a memory leak:

    wlan0: Allocated STA 74:83:c2:64:0b:87
    wlan0: Allocated STA 74:83:c2:64:0b:87
    wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_add_sta)
    wlan0: Adding new IBSS station 74:83:c2:64:0b:87
    wlan0: moving STA 74:83:c2:64:0b:87 to state 2
    wlan0: moving STA 74:83:c2:64:0b:87 to state 3
    wlan0: Inserted STA 74:83:c2:64:0b:87
    wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_work)
    wlan0: Adding new IBSS station 74:83:c2:64:0b:87
    wlan0: moving STA 74:83:c2:64:0b:87 to state 2
    wlan0: moving STA 74:83:c2:64:0b:87 to state 3
    .
    .
    wlan0: expiring inactive not authorized STA 74:83:c2:64:0b:87
    wlan0: moving STA 74:83:c2:64:0b:87 to state 2
    wlan0: moving STA 74:83:c2:64:0b:87 to state 1
    wlan0: Removed STA 74:83:c2:64:0b:87
    wlan0: Destroyed STA 74:83:c2:64:0b:87

    The ieee80211_ibss_finish_sta() is called twice on the same STA from 2
    different locations. On the second attempt, the allocated STA is not
    destroyed creating a kernel memory leak.

    This is happening because sta_info_insert_finish() does not call
    sta_info_free() the second time when the STA already exists (returns
    -EEXIST). Note that the caller sta_info_insert_rcu() assumes STA is
    destroyed upon errors.

    Same fix is applied to -ENOMEM.

    Signed-off-by: Ahmed Zaki <anzaki@gmail.com>
    Link: https://lore.kernel.org/r/20211002145329.3125293-1-anzaki@gmail.com
    [change the error path label to use the existing code]
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Viacheslav Sablin <sablin@ispras.ru>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/mac80211/sta_info.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- a/net/mac80211/sta_info.c
    +++ b/net/mac80211/sta_info.c
    @@ -645,13 +645,13 @@ static int sta_info_insert_finish(struct
    /* check if STA exists already */
    if (sta_info_get_bss(sdata, sta->sta.addr)) {
    err = -EEXIST;
    - goto out_err;
    + goto out_cleanup;
    }

    sinfo = kzalloc(sizeof(struct station_info), GFP_KERNEL);
    if (!sinfo) {
    err = -ENOMEM;
    - goto out_err;
    + goto out_cleanup;
    }

    local->num_sta++;
    @@ -707,8 +707,8 @@ static int sta_info_insert_finish(struct
    out_drop_sta:
    local->num_sta--;
    synchronize_net();
    + out_cleanup:
    cleanup_single_sta(sta);
    - out_err:
    mutex_unlock(&local->sta_mtx);
    kfree(sinfo);
    rcu_read_lock();

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