mfd: wm831x-auxadc: Prevent use after free in wm831x_auxadc_read_irq()

BugLink: https://bugs.launchpad.net/bugs/1918974
[ Upstream commit 26783d74cc6a440ee3ef9836a008a697981013d0 ]

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 <dan.carpenter@oracle.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/drivers/mfd/wm831x-auxadc.c b/drivers/mfd/wm831x-auxadc.c
index 8a7cc0f86958bb59beedfab949447c773d907d0d..65b98f3fbd929100391913cb9faae2744c1ca08b 100644 (file)
--- 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);