Re: [PATCH] reset: fix potential null pointer dereference on pointer dev

From: Philipp Zabel
Date: Fri May 10 2019 - 05:15:52 EST


Hi Colin,

[added Bartosz to Cc:]

On Thu, 2019-05-09 at 17:00 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> Pointer dev is being dereferenced when passed to the inlined
> functon dev_name, however, dev is later being null checked.
> Thus there is a potential null pointer dereference on a null
> dev. Fix this by performing the null check on dev before
> dereferencing it.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 6691dffab0ab ("reset: add support for non-DT systems")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
> drivers/reset/core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index 81ea77cba123..83f1a1d5ee67 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
> @@ -691,12 +691,13 @@ __reset_control_get_from_lookup(struct device *dev, const char *con_id,
> {
> const struct reset_control_lookup *lookup;
> struct reset_controller_dev *rcdev;
> - const char *dev_id = dev_name(dev);
> + const char *dev_id;
> struct reset_control *rstc = NULL;
>
> if (!dev)
> return ERR_PTR(-EINVAL);

Thank you for the patch. I think this check should be removed instead,
though, as __reset_control_get_from_lookup is only ever called from
__reset_control_get, right after checking dev->of_node. So dev can not
be NULL here.

regards
Philipp