2020-05-02 21:13:24

by Qiushi Wu

[permalink] [raw]

Subject: [PATCH] power: supply: fix memory leaks

---

From: Qiushi Wu <[email protected]>

In function power_supply_add_hwmon_sysfs(), psyhw->props is
allocated by bitmap_zalloc(). But this pointer is not deallocated
in several error paths, which lead to memory leak bugs. To fix
this, we can call bitmap_free() to free this pointer.

Signed-off-by: Qiushi Wu <[email protected]>
---
drivers/power/supply/power_supply_hwmon.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
index 75cf861ba492..7453390ab7a4 100644
--- a/drivers/power/supply/power_supply_hwmon.c
+++ b/drivers/power/supply/power_supply_hwmon.c
@@ -307,7 +307,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
ret = devm_add_action(dev, power_supply_hwmon_bitmap_free,
psyhw->props);
if (ret)
- goto error;
+ goto out_free;

for (i = 0; i < desc->num_properties; i++) {
const enum power_supply_property prop = desc->properties[i];
@@ -342,7 +342,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
new_name = devm_kstrdup(dev, name, GFP_KERNEL);
if (!new_name) {
ret = -ENOMEM;
- goto error;
+ goto out_free;
}
strreplace(new_name, '-', '_');
name = new_name;
@@ -353,10 +353,12 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
NULL);
ret = PTR_ERR_OR_ZERO(hwmon);
if (ret)
- goto error;
+ goto out_free;

devres_close_group(dev, power_supply_add_hwmon_sysfs);
return 0;
+out_free:
+ bitmap_free(psyhw->props);
error:
devres_release_group(dev, NULL);
return ret;
--
2.17.1

2020-05-02 22:44:02

by Sebastian Reichel

[permalink] [raw]

Subject: Re: [PATCH] power: supply: fix memory leaks

---

Hi,

On Sat, May 02, 2020 at 04:10:56PM -0500, [email protected] wrote:
> From: Qiushi Wu <[email protected]>
>
> In function power_supply_add_hwmon_sysfs(), psyhw->props is
> allocated by bitmap_zalloc(). But this pointer is not deallocated
> in several error paths, which lead to memory leak bugs. To fix
> this, we can call bitmap_free() to free this pointer.
>
> Signed-off-by: Qiushi Wu <[email protected]>
> ---

You are correct, that there is a problem in the first instance, but
the other changes are incorrect and introduce a new double free. Please
read documentation for devm_add_action(). The proper fix is to just
replace the call to devm_add_action() with devm_add_action_or_reset().
Please send a new version for this. Also please add the following
tag:

Fixes: e67d4dfc9ff19 ("power: supply: Add HWMON compatibility layer")

Thanks,

-- Sebastian

> drivers/power/supply/power_supply_hwmon.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
> index 75cf861ba492..7453390ab7a4 100644
> --- a/drivers/power/supply/power_supply_hwmon.c
> +++ b/drivers/power/supply/power_supply_hwmon.c
> @@ -307,7 +307,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
> ret = devm_add_action(dev, power_supply_hwmon_bitmap_free,
> psyhw->props);
> if (ret)
> - goto error;
> + goto out_free;
>
> for (i = 0; i < desc->num_properties; i++) {
> const enum power_supply_property prop = desc->properties[i];
> @@ -342,7 +342,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
> new_name = devm_kstrdup(dev, name, GFP_KERNEL);
> if (!new_name) {
> ret = -ENOMEM;
> - goto error;
> + goto out_free;
> }
> strreplace(new_name, '-', '_');
> name = new_name;
> @@ -353,10 +353,12 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
> NULL);
> ret = PTR_ERR_OR_ZERO(hwmon);
> if (ret)
> - goto error;
> + goto out_free;
>
> devres_close_group(dev, power_supply_add_hwmon_sysfs);
> return 0;
> +out_free:
> + bitmap_free(psyhw->props);
> error:
> devres_release_group(dev, NULL);
> return ret;
> --
> 2.17.1
>

---

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