firmware: thead,th1520-aon: Fix use after free in th1520_aon_init()

[PATCH next] firmware: thead,th1520-aon: Fix use after free in th1520_aon_init()

Posted by Dan Carpenter 9 months, 1 week ago

Record the error code before freeing "aon_chan" to avoid a
use after free.

Fixes: e4b3cbd840e5 ("firmware: thead: Add AON firmware protocol driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/firmware/thead,th1520-aon.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/thead,th1520-aon.c b/drivers/firmware/thead,th1520-aon.c
index 4416e9bbf854..38f812ac9920 100644
--- a/drivers/firmware/thead,th1520-aon.c
+++ b/drivers/firmware/thead,th1520-aon.c
@@ -203,6 +203,7 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
 {
 	struct th1520_aon_chan *aon_chan;
 	struct mbox_client *cl;
+	int ret;
 
 	aon_chan = kzalloc(sizeof(*aon_chan), GFP_KERNEL);
 	if (!aon_chan)
@@ -217,8 +218,9 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
 	aon_chan->ch = mbox_request_channel_byname(cl, "aon");
 	if (IS_ERR(aon_chan->ch)) {
 		dev_err(dev, "Failed to request aon mbox chan\n");
+		ret = PTR_ERR(aon_chan->ch);
 		kfree(aon_chan);
-		return ERR_CAST(aon_chan->ch);
+		return ERR_PTR(ret);
 	}
 
 	mutex_init(&aon_chan->transaction_lock);
-- 
2.47.2

Re: [PATCH next] firmware: thead,th1520-aon: Fix use after free in th1520_aon_init()

Posted by Ulf Hansson 9 months ago

On Sat, 15 Mar 2025 at 11:04, Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> Record the error code before freeing "aon_chan" to avoid a
> use after free.
>
> Fixes: e4b3cbd840e5 ("firmware: thead: Add AON firmware protocol driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/firmware/thead,th1520-aon.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/thead,th1520-aon.c b/drivers/firmware/thead,th1520-aon.c
> index 4416e9bbf854..38f812ac9920 100644
> --- a/drivers/firmware/thead,th1520-aon.c
> +++ b/drivers/firmware/thead,th1520-aon.c
> @@ -203,6 +203,7 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
>  {
>         struct th1520_aon_chan *aon_chan;
>         struct mbox_client *cl;
> +       int ret;
>
>         aon_chan = kzalloc(sizeof(*aon_chan), GFP_KERNEL);
>         if (!aon_chan)
> @@ -217,8 +218,9 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
>         aon_chan->ch = mbox_request_channel_byname(cl, "aon");
>         if (IS_ERR(aon_chan->ch)) {
>                 dev_err(dev, "Failed to request aon mbox chan\n");
> +               ret = PTR_ERR(aon_chan->ch);
>                 kfree(aon_chan);
> -               return ERR_CAST(aon_chan->ch);
> +               return ERR_PTR(ret);
>         }
>
>         mutex_init(&aon_chan->transaction_lock);
> --
> 2.47.2
>

Re: [PATCH next] firmware: thead,th1520-aon: Fix use after free in th1520_aon_init()

Posted by Markus Elfring 9 months ago

> Record the error code before freeing "aon_chan" to avoid a
> use after free.

Would it become helpful to mention which selection of source code
analysis tools detected such a questionable implementation detail?


…
> +++ b/drivers/firmware/thead,th1520-aon.c
> @@ -203,6 +203,7 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
>  {
>  	struct th1520_aon_chan *aon_chan;
>  	struct mbox_client *cl;
> +	int ret;
>
>  	aon_chan = kzalloc(sizeof(*aon_chan), GFP_KERNEL);
>  	if (!aon_chan)
> @@ -217,8 +218,9 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
>  	aon_chan->ch = mbox_request_channel_byname(cl, "aon");
>  	if (IS_ERR(aon_chan->ch)) {
>  		dev_err(dev, "Failed to request aon mbox chan\n");
> +		ret = PTR_ERR(aon_chan->ch);
>  		kfree(aon_chan);
> -		return ERR_CAST(aon_chan->ch);
> +		return ERR_PTR(ret);
>  	}
>
>  	mutex_init(&aon_chan->transaction_lock);

May the additional variable (for an information) be defined only for
the affected if branch?
Would a smaller scope be more appropriate here?

Regards,
Markus

Re: [PATCH next] firmware: thead,th1520-aon: Fix use after free in th1520_aon_init()

Posted by Dan Carpenter 9 months ago

On Sun, Mar 16, 2025 at 01:05:08PM +0100, Markus Elfring wrote:
> > +++ b/drivers/firmware/thead,th1520-aon.c
> > @@ -203,6 +203,7 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
> >  {
> >  	struct th1520_aon_chan *aon_chan;
> >  	struct mbox_client *cl;
> > +	int ret;
> >
> >  	aon_chan = kzalloc(sizeof(*aon_chan), GFP_KERNEL);
> >  	if (!aon_chan)
> > @@ -217,8 +218,9 @@ struct th1520_aon_chan *th1520_aon_init(struct device *dev)
> >  	aon_chan->ch = mbox_request_channel_byname(cl, "aon");
> >  	if (IS_ERR(aon_chan->ch)) {
> >  		dev_err(dev, "Failed to request aon mbox chan\n");
> > +		ret = PTR_ERR(aon_chan->ch);
> >  		kfree(aon_chan);
> > -		return ERR_CAST(aon_chan->ch);
> > +		return ERR_PTR(ret);
> >  	}
> >
> >  	mutex_init(&aon_chan->transaction_lock);
> 
> May the additional variable (for an information) be defined only for
> the affected if branch?
> Would a smaller scope be more appropriate here?

There are some variables which should always be at function scope and
"int ret" is one of those.

regards,
dan carpenter