2006-09-28 23:45:31

by Florin Malita

Subject: [PATCH] Dereference after free in snd_hwdep_release()

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 <[email protected]>
---

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;
}

2006-09-29 10:55:00

by Takashi Iwai

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 <[email protected]>

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;
> }
>
>
>