linux-kernel - Re: [PATCH] staging: greybus: don't use index pointer after iter

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Date:   Thu, 7 Jul 2022 12:52:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Karthik Alapati <mail@...thek.com>
Cc:     Johan Hovold <johan@...nel.org>, Alex Elder <elder@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        greybus-dev@...ts.linaro.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: greybus: don't use index pointer after iter

On Thu, Jul 07, 2022 at 03:59:54PM +0530, Karthik Alapati wrote:
> There are some usages of index pointer of list(w) which may not point to
> the right entry when the required entry is not found and the list traversal
> completes with index pointer pointing to the last entry. So, use w_found
> flag to track the case where the entry is found.

That is already being done here with the use of the w variable.

Look at commit 80c968a04a38 ("staging: greybus: audio: fix loop cursor
use after iteration") and then d2b47721a100 ("staging: greybus: audio:
replace safe list iteration").

> diff --git a/drivers/staging/greybus/audio_helper.c b/drivers/staging/greybus/audio_helper.c
> index 843760675876..7c04897a22a2 100644
> --- a/drivers/staging/greybus/audio_helper.c
> +++ b/drivers/staging/greybus/audio_helper.c
> @@ -116,6 +116,7 @@ int gbaudio_dapm_free_controls(struct snd_soc_dapm_context *dapm,
>  {
>  	int i;
>  	struct snd_soc_dapm_widget *w, *next_w;
> +	bool w_found = false;
>  #ifdef CONFIG_DEBUG_FS
>  	struct dentry *parent = dapm->debugfs_dapm;
>  	struct dentry *debugfs_w = NULL;
> @@ -124,15 +125,18 @@ int gbaudio_dapm_free_controls(struct snd_soc_dapm_context *dapm,
>  	mutex_lock(&dapm->card->dapm_mutex);
>  	for (i = 0; i < num; i++) {
>  		/* below logic can be optimized to identify widget pointer */
> +		w_found = false
>  		list_for_each_entry_safe(w, next_w, &dapm->card->widgets,
>  					 list) {

You are working off of an old kernel version here, please see the above
commits which do not seem to be in your tree.  Always work on linux-next
for issues so that you do not duplicate work that others have completed.

thanks,

greg k-h