linux-kernel - Re: [PATCH] Dereference after free in snd_hwdep

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Date:	Fri, 29 Sep 2006 12:54:57 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Florin Malita <fmalita@...il.com>
Cc:	perex@...e.cz, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Dereference after free in snd_hwdep_release()

At Thu, 28 Sep 2006 19:45:50 -0400,
Florin Malita wrote:
> 
> snd_card_file_remove() may free hw->card so we can't dereference
> hw->card->module after that.
> 
> Coverity ID 1420.
> 
> Signed-off-by: Florin Malita <fmalita@...il.com>

Thanks!  Applied to ALSA tree now.


Takashi

> ---
> 
> diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
> index 9aa9d94..46b4768 100644
> --- a/sound/core/hwdep.c
> +++ b/sound/core/hwdep.c
> @@ -158,6 +158,7 @@ static int snd_hwdep_release(struct inod
>  {
>  	int err = -ENXIO;
>  	struct snd_hwdep *hw = file->private_data;
> +	struct module *mod = hw->card->module;
>  	mutex_lock(&hw->open_mutex);
>  	if (hw->ops.release) {
>  		err = hw->ops.release(hw, file);
> @@ -167,7 +168,7 @@ static int snd_hwdep_release(struct inod
>  		hw->used--;
>  	snd_card_file_remove(hw->card, file);
>  	mutex_unlock(&hw->open_mutex);
> -	module_put(hw->card->module);
> +	module_put(mod);
>  	return err;
>  }
>  
> 
> 
-
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