linux-kernel - [PATCH] regulator: core: fix NULL dereference on unbind due to stale coupling data

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Message-Id: <20250626083809.314842-1-acarmina@redhat.com>
Date: Thu, 26 Jun 2025 08:38:09 +0000
From: Alessandro Carminati <acarmina@...hat.com>
To: Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	Dmitry Osipenko <digetx@...il.com>,
	Alessandro Carminati <alessandro.carminati@...il.com>,
	Alessandro Carminati <acarmina@...hat.com>
Subject: [PATCH] regulator: core: fix NULL dereference on unbind due to stale coupling data

Failing to reset coupling_desc.n_coupled after freeing coupled_rdevs can
lead to NULL pointer dereference when regulators are accessed post-unbind.

This can happen during runtime PM or other regulator operations that rely
on coupling metadata.

For example, on ridesx4, unbinding the 'reg-dummy' platform device triggers
a panic in regulator_lock_recursive() due to stale coupling state.

Ensure n_coupled is set to 0 to prevent access to invalid pointers.

Signed-off-by: Alessandro Carminati <acarmina@...hat.com>
---
 drivers/regulator/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 7a248dc8d2e2..cbd6d53ebfb5 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5639,6 +5639,7 @@ static void regulator_remove_coupling(struct regulator_dev *rdev)
 				 ERR_PTR(err));
 	}

+	rdev->coupling_desc.n_coupled = 0;
 	kfree(rdev->coupling_desc.coupled_rdevs);
 	rdev->coupling_desc.coupled_rdevs = NULL;
 }
-- 
2.34.1