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    Subject[PATCH 4.19 28/48] atm: fix atm_dev refcnt leaks in atmtcp_remove_persistent
    Date
    From: Xin Xiong <xiongx18@fudan.edu.cn>

    [ Upstream commit 51875dad43b44241b46a569493f1e4bfa0386d86 ]

    atmtcp_remove_persistent() invokes atm_dev_lookup(), which returns a
    reference of atm_dev with increased refcount or NULL if fails.

    The refcount leaks issues occur in two error handling paths. If
    dev_data->persist is zero or PRIV(dev)->vcc isn't NULL, the function
    returns 0 without decreasing the refcount kept by a local variable,
    resulting in refcount leaks.

    Fix the issue by adding atm_dev_put() before returning 0 both when
    dev_data->persist is zero or PRIV(dev)->vcc isn't NULL.

    Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
    Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
    Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/atm/atmtcp.c | 10 ++++++++--
    1 file changed, 8 insertions(+), 2 deletions(-)

    diff --git a/drivers/atm/atmtcp.c b/drivers/atm/atmtcp.c
    index afebeb1c3e1e9..723bad1201cc5 100644
    --- a/drivers/atm/atmtcp.c
    +++ b/drivers/atm/atmtcp.c
    @@ -432,9 +432,15 @@ static int atmtcp_remove_persistent(int itf)
    return -EMEDIUMTYPE;
    }
    dev_data = PRIV(dev);
    - if (!dev_data->persist) return 0;
    + if (!dev_data->persist) {
    + atm_dev_put(dev);
    + return 0;
    + }
    dev_data->persist = 0;
    - if (PRIV(dev)->vcc) return 0;
    + if (PRIV(dev)->vcc) {
    + atm_dev_put(dev);
    + return 0;
    + }
    kfree(dev_data);
    atm_dev_put(dev);
    atm_dev_deregister(dev);
    --
    2.25.1


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