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SubjectRe: [PATCH 2/2] i2c: Fix a potential use after free
On Fri, Dec 27, 2019 at 09:34:32AM +0000, Xu Wang wrote:
> 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.
>
> Signed-off-by: Xu Wang <vulab@iscas.ac.cn>

Do you have a testcase to reproduce it?

I wonder because we are freeing the device structure which is embedded
inside the adap structure, not the adap structure itself. Or?

> ---
> drivers/i2c/i2c-core-base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 9f8dcd3..160d43e 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -2301,8 +2301,8 @@ void i2c_put_adapter(struct i2c_adapter *adap)
> if (!adap)
> return;
>
> - put_device(&adap->dev);
> module_put(adap->owner);
> + put_device(&adap->dev);
> }
> EXPORT_SYMBOL(i2c_put_adapter);
>
> --
> 2.7.4
>
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