Re: [PATCH][next] pinctrl: pinctrl-single: add allocation failure checking of saved_vals

From: Johan Hovold
Date: Thu Jun 07 2018 - 03:29:55 EST


On Wed, Jun 06, 2018 at 02:43:38PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> Currently saved_vals is being allocated and there is no check for
> failed allocation (which is more likely than normal when using
> GFP_ATOMIC). Fix this by checking for a failed allocation and
> propagating this error return down the the caller chain.
>
> Detected by CoverityScan, CID#1469841 ("Dereference null return value")
> Fixes: 88a1dbdec682 ("pinctrl: pinctrl-single: Add functions to save and restore pinctrl context")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
> drivers/pinctrl/pinctrl-single.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
> index 9c3c00515aa0..0905ee002041 100644
> --- a/drivers/pinctrl/pinctrl-single.c
> +++ b/drivers/pinctrl/pinctrl-single.c
> @@ -1588,8 +1588,11 @@ static int pcs_save_context(struct pcs_device *pcs)
>
> mux_bytes = pcs->width / BITS_PER_BYTE;
>
> - if (!pcs->saved_vals)
> + if (!pcs->saved_vals) {
> pcs->saved_vals = devm_kzalloc(pcs->dev, pcs->size, GFP_ATOMIC);
> + if (!pcs->saved_vals)
> + return -ENOMEM;
> + }
>
> switch (pcs->width) {
> case 64:
> @@ -1649,8 +1652,13 @@ static int pinctrl_single_suspend(struct platform_device *pdev,
> if (!pcs)
> return -EINVAL;
>
> - if (pcs->flags & PCS_CONTEXT_LOSS_OFF)
> - pcs_save_context(pcs);
> + if (pcs->flags & PCS_CONTEXT_LOSS_OFF) {
> + int ret;
> +
> + ret = pcs_save_context(pcs);
> + if (ret < 0)
> + return ret;
> + }

This appears to be the right fix (along the lines of what the author may
have intended by having the helper return an int), but as a follow-up
patch, why not move the allocation to probe() instead?

Also this doesn't look like something that requires atomic allocation in
the first place, GFP_KERNEL should do for the legacy suspend callback.

> return pinctrl_force_sleep(pcs->pctl);
> }

But for this fix, feel free to add:

Reviewed-by: Johan Hovold <johan@xxxxxxxxxx>

Thanks,
Johan