[PATCH 4.14 091/122] reset: Fix potential use-after-free in __of_reset_control_get()

Greg Kroah-Hartman
2019-11-22T10:53:54Z

From: Geert Uytterhoeven <geert+renesas@glider.be>

[ 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>
---
drivers/reset/core.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index da4292e9de978..72b96b5c75a8f 100644
--- 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;
}
--
2.20.1