Subject: Re: [PATCH] net: mwifiex: fix a NULL pointer dereference

From: Brian Norris <[email-masked]>
Date: Mon, 11 Mar 2019 10:24:21 -0700

On Mon, Mar 11, 2019 at 02:43:47AM -0500, Kangjie Lu wrote:
> In case dev_alloc_skb fails, the fix returns -ENOMEM to avoid
> NULL pointer dereference.
> 
> Signed-off-by: Kangjie Lu <[email-masked]>
> ---
>  drivers/net/wireless/marvell/mwifiex/cmdevt.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/wireless/marvell/mwifiex/cmdevt.c b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
> index 60db2b969e20..5565f18039ab 100644
> --- a/drivers/net/wireless/marvell/mwifiex/cmdevt.c
> +++ b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
> @@ -341,6 +341,12 @@ static int mwifiex_dnld_sleep_confirm_cmd(struct mwifiex_adapter *adapter)
>  		sleep_cfm_tmp =
>  			dev_alloc_skb(sizeof(struct mwifiex_opt_sleep_confirm)
>  				      + MWIFIEX_TYPE_LEN);
> +		if (!sleep_cfm_tmp) {
> +			mwifiex_dbg(adapter, ERROR, 

You have trailing whitespace. Please run your patches through
scripts/checkpatch.pl.

> +				    "SLEEP_CFM: dev_alloc_skb failed\n");
> +			return -ENOMEM;

It's not exactly a problem with your patch, but nobody really checks the
return status of this function. I think in most (all?) cases, that's
probably OK, because we also implicitly communicate the success/failure
of this function by modifying the ->ps_state field (basically, a state
machine). So this is probably OK.

Other than the whitespace:

Reviewed-by: Brian Norris <[email-masked]>

> +		}
> +
>  		skb_put(sleep_cfm_tmp, sizeof(struct mwifiex_opt_sleep_confirm)
>  			+ MWIFIEX_TYPE_LEN);
>  		put_unaligned_le32(MWIFIEX_USB_TYPE_CMD, sleep_cfm_tmp->data);
> -- 
> 2.17.1
>