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    Subject[PATCH 4.9 20/90] batman-adv: Fix refcnt leak in batadv_show_throughput_override
    Date
    From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

    commit f872de8185acf1b48b954ba5bd8f9bc0a0d14016 upstream.

    batadv_show_throughput_override() invokes batadv_hardif_get_by_netdev(),
    which gets a batadv_hard_iface object from net_dev with increased refcnt
    and its reference is assigned to a local pointer 'hard_iface'.

    When batadv_show_throughput_override() returns, "hard_iface" becomes
    invalid, so the refcount should be decreased to keep refcount balanced.

    The issue happens in the normal path of
    batadv_show_throughput_override(), which forgets to decrease the refcnt
    increased by batadv_hardif_get_by_netdev() before the function returns,
    causing a refcnt leak.

    Fix this issue by calling batadv_hardif_put() before the
    batadv_show_throughput_override() returns in the normal path.

    Fixes: 0b5ecc6811bd ("batman-adv: add throughput override attribute to hard_ifaces")
    Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
    Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
    Signed-off-by: Sven Eckelmann <sven@narfation.org>
    Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/batman-adv/sysfs.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/net/batman-adv/sysfs.c
    +++ b/net/batman-adv/sysfs.c
    @@ -1120,6 +1120,7 @@ static ssize_t batadv_show_throughput_ov

    tp_override = atomic_read(&hard_iface->bat_v.throughput_override);

    + batadv_hardif_put(hard_iface);
    return sprintf(buff, "%u.%u MBit\n", tp_override / 10,
    tp_override % 10);
    }

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