[PATCH 4.19 07/41] reset: Fix crash when freeing non-existent optional resets

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

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

[ Upstream commit 4a6756f56bcf8e64c87144a626ce53aea4899c0e ]

When obtaining one or more optional resets, non-existent resets are
stored as NULL pointers, and all related error and cleanup paths need to
take this into account.

Currently only reset_control_put() and reset_control_bulk_put()
get this right.  All of __reset_control_bulk_get(),
of_reset_control_array_get(), and reset_control_array_put() lack the
proper checking, causing NULL pointer dereferences on failure or
release.

Fix this by moving the existing check from reset_control_bulk_put() to
__reset_control_put_internal(), so it applies to all callers.
The double check in reset_control_put() doesn't hurt.

Fixes: 17c82e206d2a3cd8 ("reset: Add APIs to manage array of resets")
Fixes: 48d71395896d54ee ("reset: Add reset_control_bulk API")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/2440edae7ca8534628cdbaf559ded288f2998178.1701276806.git.geert+renesas@glider.be
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/reset/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index ccb97f4e31c38..1680d27040c9b 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -459,6 +459,9 @@ static void __reset_control_put_internal(struct reset_control *rstc)
 {
 	lockdep_assert_held(&reset_list_mutex);
 
+	if (IS_ERR_OR_NULL(rstc))
+		return;
+
 	kref_put(&rstc->refcnt, __reset_control_release);
 }
 
-- 
2.43.0