Unverified Commit 0a7416f9 authored Aug 31, 2020 by Dmitry Osipenko Committed by Mark Brown Sep 01, 2020

regulator: core: Fix slab-out-of-bounds in regulator_unlock_recursive()

The recent commit 7d819664 ("regulator: Remove pointer table
overallocation") changed the size of coupled_rdevs and now KASAN is able
to detect slab-out-of-bounds problem in regulator_unlock_recursive(),
which is a legit problem caused by a typo in the code. The recursive
unlock function uses n_coupled value of a parent regulator for unlocking
supply regulator, while supply's n_coupled should be used. In practice
problem may only affect platforms that use coupled regulators.

Cc: stable@vger.kernel.org # 5.0+
Fixes: f8702f9e ("regulator: core: Use ww_mutex for regulators locking")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20200831204335.19489-1-digetx@gmail.com

Signed-off-by: Mark Brown <broonie@kernel.org>

parent 3bec5b6a

drivers/regulator/core.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -236,8 +236,8 @@ static bool regulator_supply_is_couple(struct regulator_dev *rdev)
		static void regulator_unlock_recursive(struct regulator_dev *rdev,
		unsigned int n_coupled)
		{
		struct regulator_dev *c_rdev;
		int i;
		struct regulator_dev c_rdev, supply_rdev;
		int i, supply_n_coupled;

		for (i = n_coupled; i > 0; i--) {
		c_rdev = rdev->coupling_desc.coupled_rdevs[i - 1];
		@@ -245,10 +245,13 @@ static void regulator_unlock_recursive(struct regulator_dev *rdev,
		if (!c_rdev)
		continue;

		if (c_rdev->supply && !regulator_supply_is_couple(c_rdev))
		regulator_unlock_recursive(
		c_rdev->supply->rdev,
		c_rdev->coupling_desc.n_coupled);
		if (c_rdev->supply && !regulator_supply_is_couple(c_rdev)) {
		supply_rdev = c_rdev->supply->rdev;
		supply_n_coupled = supply_rdev->coupling_desc.n_coupled;

		regulator_unlock_recursive(supply_rdev,
		supply_n_coupled);
		}

		regulator_unlock(c_rdev);
		}

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