[PATCH AUTOSEL 5.8 47/72] regulator: fix memory leak on error path of regulator_register()

Sasha Levin
2020-08-08T23:49:53Z

From: Vladimir Zapolskiy <vz@mleia.com>

[ Upstream commit 9177514ce34902b3adb2abd490b6ad05d1cfcb43 ]

The change corrects registration and deregistration on error path
of a regulator, the problem was manifested by a reported memory
leak on deferred probe:

as3722-regulator as3722-regulator: regulator 13 register failed -517

# cat /sys/kernel/debug/kmemleak
unreferenced object 0xecc43740 (size 64):
comm "swapper/0", pid 1, jiffies 4294937640 (age 712.880s)
hex dump (first 32 bytes):
72 65 67 75 6c 61 74 6f 72 2e 32 34 00 5a 5a 5a regulator.24.ZZZ
5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
backtrace:
[<0c4c3d1c>] __kmalloc_track_caller+0x15c/0x2c0
[<40c0ad48>] kvasprintf+0x64/0xd4
[<109abd29>] kvasprintf_const+0x70/0x84
[<c4215946>] kobject_set_name_vargs+0x34/0xa8
[<62282ea2>] dev_set_name+0x40/0x64
[<a39b6757>] regulator_register+0x3a4/0x1344
[<16a9543f>] devm_regulator_register+0x4c/0x84
[<51a4c6a1>] as3722_regulator_probe+0x294/0x754
...

The memory leak problem was introduced as a side ef another fix in
regulator_register() error path, I believe that the proper fix is
to decouple device_register() function into its two compounds and
initialize a struct device before assigning any values to its fields
and then using it before actual registration of a device happens.

This lets to call put_device() safely after initialization, and, since
now a release callback is called, kfree(rdev->constraints) shall be
removed to exclude a double free condition.

Fixes: a3cde9534ebd ("regulator: core: fix regulator_register() error paths to properly release rdev")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Cc: Wen Yang <wenyang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20200724005013.23278-1-vz@mleia.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/regulator/core.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 03154f5b939f7..720f28844795b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5023,7 +5023,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
struct regulator_dev *rdev;
bool dangling_cfg_gpiod = false;
bool dangling_of_gpiod = false;
- bool reg_device_fail = false;
struct device *dev;
int ret, i;

@@ -5152,10 +5151,12 @@ regulator_register(const struct regulator_desc *regulator_desc,
}

/* register with sysfs */
+ device_initialize(&rdev->dev);
rdev->dev.class = &regulator_class;
rdev->dev.parent = dev;
dev_set_name(&rdev->dev, "regulator.%lu",
(unsigned long) atomic_inc_return(&regulator_no));
+ dev_set_drvdata(&rdev->dev, rdev);

/* set regulator constraints */
if (init_data)
@@ -5206,12 +5207,9 @@ regulator_register(const struct regulator_desc *regulator_desc,
!rdev->desc->fixed_uV)
rdev->is_switch = true;

- dev_set_drvdata(&rdev->dev, rdev);
- ret = device_register(&rdev->dev);
- if (ret != 0) {
- reg_device_fail = true;
+ ret = device_add(&rdev->dev);
+ if (ret != 0)
goto unset_supplies;
- }

rdev_init_debugfs(rdev);

@@ -5233,17 +5231,15 @@ regulator_register(const struct regulator_desc *regulator_desc,
mutex_unlock(&regulator_list_mutex);
wash:
kfree(rdev->coupling_desc.coupled_rdevs);
- kfree(rdev->constraints);
mutex_lock(&regulator_list_mutex);
regulator_ena_gpio_free(rdev);
mutex_unlock(&regulator_list_mutex);
+ put_device(&rdev->dev);
+ rdev = NULL;
clean:
if (dangling_of_gpiod)
gpiod_put(config->ena_gpiod);
- if (reg_device_fail)
- put_device(&rdev->dev);
- else
- kfree(rdev);
+ kfree(rdev);
kfree(config);
rinse:
if (dangling_cfg_gpiod)
--
2.25.1