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    Subject[PATCH 5.7 133/477] staging: gasket: Fix mapping refcnt leak when put attribute fails
    Date
    From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

    [ Upstream commit 57a66838e1494cd881b7f4e110ec685736e8e3ca ]

    gasket_sysfs_put_attr() invokes get_mapping(), which returns a reference
    of the specified gasket_sysfs_mapping object to "mapping" with increased
    refcnt.

    When gasket_sysfs_put_attr() returns, local variable "mapping" becomes
    invalid, so the refcount should be decreased to keep refcount balanced.

    The reference counting issue happens in one path of
    gasket_sysfs_put_attr(). When mapping attribute is unknown, the function
    forgets to decrease the refcnt increased by get_mapping(), causing a
    refcnt leak.

    Fix this issue by calling put_mapping() when put attribute fails due to
    unknown attribute.

    Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
    Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
    Link: https://lore.kernel.org/r/1587618895-13660-1-git-send-email-xiyuyang19@fudan.edu.cn
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/staging/gasket/gasket_sysfs.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
    index 5f0e089573a29..ad852ea1d4a92 100644
    --- a/drivers/staging/gasket/gasket_sysfs.c
    +++ b/drivers/staging/gasket/gasket_sysfs.c
    @@ -339,6 +339,7 @@ void gasket_sysfs_put_attr(struct device *device,

    dev_err(device, "Unable to put unknown attribute: %s\n",
    attr->attr.attr.name);
    + put_mapping(mapping);
    }
    EXPORT_SYMBOL(gasket_sysfs_put_attr);

    --
    2.25.1


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