On 18 October 2016 at 10:43, Maxime Ripard
<maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> mmc_regulator_get_supply might silently fail if the regulators are not
> found, which is the right thing to do since both these regulators are
> optional.
>
> However, the drivers then have no way to know whether or not they should
> proceed and call mmc_regulator_set_ocr. And since this function doesn't
Host drivers should check "if (!IS_ERR(mmc->supply.vmmc))" before
invoking mmc_regulator_set_ocr(). I wasn't aware that some didn't.
My point is, that in some cases the regulator is optional, then a host
driver need to take other actions to power on/off the card. So, I am
wondering whether adding these checks in mmc_regulator_set_ocr() is a
bit unnecessary, as the host drivers are already checking the
IS_ERR().
> check for the validity of the regulator pointer, it leads to a null pointer
> dereference. Add such a check to make sure everything works fine.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/mmc/core/core.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 2553d903a82b..1d3ea5e1aa37 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1474,6 +1474,12 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
> int result = 0;
> int min_uV, max_uV;
>
> + if (!supply)
> + return -EINVAL;
> +
> + if (IS_ERR(supply))
> + return PTR_ERR(supply);
> +
> if (vdd_bit) {
> mmc_ocrbitnum_to_vdd(vdd_bit, &min_uV, &max_uV);
>
> --
> 2.9.3
>
Kind regards
Uffe
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