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Subject[PATCH v1] regulator: core: Fix slab-out-of-bounds in regulator_unlock_recursive()
Date
The recent commit 7d8196641ee1 ("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: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/regulator/core.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 5eda1927a4aa..8796c9a24b28 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -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);
}
--
2.27.0
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