Re: [arm] BUG: KASAN: slab-out-of-bounds in memcmp+0x30/0x5c

[Arnd Bergmann]

On Wed, Nov 18, 2020 at 12:24 AM Nishanth Menon <nm@xxxxxx> wrote:
> On 16:25-20201117, Arnd Bergmann wrote:
>
> Yes, this was indeed a bug that has been around for some time now :(
>
> I tested with a variant of the above (did'nt like that
> oinfo was being assigned an invalid address)
> Boot log: https://pastebin.ubuntu.com/p/nZfz3HF8N6/ (with the same
> config as in the report): Would you prefer to me to send the following
> as a formal patch?

Awesome, thanks for the new patch and testing it!

Yes, please send this as a proper patch to have it picked up
into the regulator tree as a bugfix.

Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>

> diff --git a/drivers/regulator/ti-abb-regulator.c b/drivers/regulator/ti-abb-regulator.c
> index 3e60bff76194..9f0a4d50cead 100644
> --- a/drivers/regulator/ti-abb-regulator.c
> +++ b/drivers/regulator/ti-abb-regulator.c
> @@ -342,8 +342,17 @@ static int ti_abb_set_voltage_sel(struct regulator_dev *rdev, unsigned sel)
>                 return ret;
>         }
>
> -       /* If data is exactly the same, then just update index, no change */
>         info = &abb->info[sel];
> +       /*
> +        * When Linux kernel is starting up, we are'nt sure of the
> +        * Bias configuration that bootloader has configured.
> +        * So, we get to know the actual setting the first time
> +        * we are asked to transition.
> +        */
> +       if (abb->current_info_idx == -EINVAL)
> +               goto just_set_abb;
> +
> +       /* If data is exactly the same, then just update index, no change */
>         oinfo = &abb->info[abb->current_info_idx];
>         if (!memcmp(info, oinfo, sizeof(*info))) {
>                 dev_dbg(dev, "%s: Same data new idx=%d, old idx=%d\n", __func__,
> @@ -351,6 +360,7 @@ static int ti_abb_set_voltage_sel(struct regulator_dev *rdev, unsigned sel)
>                 goto out;
>         }
>
> +just_set_abb:
>         ret = ti_abb_set_opp(rdev, abb, info);
>
>  out: