2020-12-14 14:46:11

by Dan Carpenter

Subject: [PATCH] mfd: wm831x-auxadc: Prevent use after free in wm831x_auxadc_read_irq()

The "req" struct is always added to the "wm831x->auxadc_pending" list,
but it's only removed from the list on the success path. If a failure
occurs then the "req" struct is freed but it's still on the list,
leading to a use after free.

Fixes: 78bb3688ea18 ("mfd: Support multiple active WM831x AUXADC conversions")
Signed-off-by: Dan Carpenter <[email protected]>
---
drivers/mfd/wm831x-auxadc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mfd/wm831x-auxadc.c b/drivers/mfd/wm831x-auxadc.c
index 8a7cc0f86958..65b98f3fbd92 100644
--- a/drivers/mfd/wm831x-auxadc.c
+++ b/drivers/mfd/wm831x-auxadc.c
@@ -93,11 +93,10 @@ static int wm831x_auxadc_read_irq(struct wm831x *wm831x,
wait_for_completion_timeout(&req->done, msecs_to_jiffies(500));

mutex_lock(&wm831x->auxadc_lock);
-
- list_del(&req->list);
ret = req->val;

out:
+ list_del(&req->list);
mutex_unlock(&wm831x->auxadc_lock);

kfree(req);
--
2.29.2

2020-12-14 15:05:21

by Charles Keepax

Subject: Re: [PATCH] mfd: wm831x-auxadc: Prevent use after free in wm831x_auxadc_read_irq()

On Mon, Dec 14, 2020 at 02:59:10PM +0300, Dan Carpenter wrote:
> The "req" struct is always added to the "wm831x->auxadc_pending" list,
> but it's only removed from the list on the success path. If a failure
> occurs then the "req" struct is freed but it's still on the list,
> leading to a use after free.
>
> Fixes: 78bb3688ea18 ("mfd: Support multiple active WM831x AUXADC conversions")
> Signed-off-by: Dan Carpenter <[email protected]>
> ---

Acked-by: Charles Keepax <[email protected]>

Thanks,
Charles