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    Subject[PATCH 5.10 176/545] i2c: Fix a potential use after free
    Date
    From: Xu Wang <vulab@iscas.ac.cn>

    [ Upstream commit e4c72c06c367758a14f227c847f9d623f1994ecf ]

    Free the adap structure only after we are done using it.
    This patch just moves the put_device() down a bit to avoid the
    use after free.

    Fixes: 611e12ea0f12 ("i2c: core: manage i2c bus device refcount in i2c_[get|put]_adapter")
    Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
    [wsa: added comment to the code, added Fixes tag]
    Signed-off-by: Wolfram Sang <wsa@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/i2c/i2c-core-base.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
    index bdce6d3e5327..34fecf97a355 100644
    --- a/drivers/i2c/i2c-core-base.c
    +++ b/drivers/i2c/i2c-core-base.c
    @@ -2405,8 +2405,9 @@ void i2c_put_adapter(struct i2c_adapter *adap)
    if (!adap)
    return;

    - put_device(&adap->dev);
    module_put(adap->owner);
    + /* Should be last, otherwise we risk use-after-free with 'adap' */
    + put_device(&adap->dev);
    }
    EXPORT_SYMBOL(i2c_put_adapter);

    --
    2.35.1


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