reset: Fix potential use-after-free in __of_reset_control_get()

BugLink: https://bugs.launchpad.net/bugs/1854216
[ Upstream commit b790c8ea5593d6dc3580adfad8e117eeb56af874 ]

Calling of_node_put() decreases the reference count of a device tree
object, and may free some data.

However, the of_phandle_args structure embedding it is passed to
reset_controller_dev.of_xlate() after that, so it may still be accessed.

Move the call to of_node_put() down to fix this.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: moved of_node_put after mutex_unlock]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index da4292e9de978a6bf0b8d9e1520dbbd41ac6cf0b..72b96b5c75a8f828200dac8cda3fc3ce48ac7b35 100644 (file)
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -466,28 +466,29 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
                        break;
                }
        }
-       of_node_put(args.np);
 
        if (!rcdev) {
-               mutex_unlock(&reset_list_mutex);
-               return ERR_PTR(-EPROBE_DEFER);
+               rstc = ERR_PTR(-EPROBE_DEFER);
+               goto out;
        }
 
        if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
-               mutex_unlock(&reset_list_mutex);
-               return ERR_PTR(-EINVAL);
+               rstc = ERR_PTR(-EINVAL);
+               goto out;
        }
 
        rstc_id = rcdev->of_xlate(rcdev, &args);
        if (rstc_id < 0) {
-               mutex_unlock(&reset_list_mutex);
-               return ERR_PTR(rstc_id);
+               rstc = ERR_PTR(rstc_id);
+               goto out;
        }
 
        /* reset_list_mutex also protects the rcdev's reset_control list */
        rstc = __reset_control_get_internal(rcdev, rstc_id, shared);
 
+out:
        mutex_unlock(&reset_list_mutex);
+       of_node_put(args.np);
 
        return rstc;
 }