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    Subject[PATCH 4.9 45/47] mac80211: free sta in sta_info_insert_finish() on errors
    Date
    From: Johannes Berg <johannes.berg@intel.com>

    commit 7bc40aedf24d31d8bea80e1161e996ef4299fb10 upstream.

    If sta_info_insert_finish() fails, we currently keep the station
    around and free it only in the caller, but there's only one such
    caller and it always frees it immediately.

    As syzbot found, another consequence of this split is that we can
    put things that sleep only into __cleanup_single_sta() and not in
    sta_info_free(), but this is the only place that requires such of
    sta_info_free() now.

    Change this to free the station in sta_info_insert_finish(), in
    which case we can still sleep. This will also let us unify the
    cleanup code later.

    Cc: stable@vger.kernel.org
    Fixes: dcd479e10a05 ("mac80211: always wind down STA state")
    Reported-by: syzbot+32c6c38c4812d22f2f0b@syzkaller.appspotmail.com
    Reported-by: syzbot+4c81fe92e372d26c4246@syzkaller.appspotmail.com
    Reported-by: syzbot+6a7fe9faf0d1d61bc24a@syzkaller.appspotmail.com
    Reported-by: syzbot+abed06851c5ffe010921@syzkaller.appspotmail.com
    Reported-by: syzbot+b7aeb9318541a1c709f1@syzkaller.appspotmail.com
    Reported-by: syzbot+d5a9416c6cafe53b5dd0@syzkaller.appspotmail.com
    Link: https://lore.kernel.org/r/20201112112201.ee6b397b9453.I9c31d667a0ea2151441cc64ed6613d36c18a48e0@changeid
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/mac80211/sta_info.c | 14 ++++----------
    1 file changed, 4 insertions(+), 10 deletions(-)

    --- a/net/mac80211/sta_info.c
    +++ b/net/mac80211/sta_info.c
    @@ -601,7 +601,7 @@ static int sta_info_insert_finish(struct
    out_drop_sta:
    local->num_sta--;
    synchronize_net();
    - __cleanup_single_sta(sta);
    + cleanup_single_sta(sta);
    out_err:
    mutex_unlock(&local->sta_mtx);
    kfree(sinfo);
    @@ -620,19 +620,13 @@ int sta_info_insert_rcu(struct sta_info

    err = sta_info_insert_check(sta);
    if (err) {
    + sta_info_free(local, sta);
    mutex_unlock(&local->sta_mtx);
    rcu_read_lock();
    - goto out_free;
    + return err;
    }

    - err = sta_info_insert_finish(sta);
    - if (err)
    - goto out_free;
    -
    - return 0;
    - out_free:
    - sta_info_free(local, sta);
    - return err;
    + return sta_info_insert_finish(sta);
    }

    int sta_info_insert(struct sta_info *sta)

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