Re: [PATCH] power: supply: fix memory leaks (v2)

[Sebastian Reichel]

Hi,

On Sat, May 02, 2020 at 06:33:38PM -0500, wu000...@umn.edu wrote:
> From: Qiushi Wu 
> 
> In function power_supply_add_hwmon_sysfs(), psyhw->props is
> allocated by bitmap_zalloc(). But this pointer is not deallocated
> when devm_add_action fail,  which lead to a memory leak bug. To fix
> this, we replace devm_add_action with devm_add_action_or_reset.
> 
> v2:
>   - Prevent introducing double-free.
>   - Added fixes tag
> 
> Fixes: e67d4dfc9ff19 ("power: supply: Add HWMON compatibility layer")
> Signed-off-by: Qiushi Wu 
> ---

Thanks, queued to power-supply's for-next branch.
Notes for next time:

* I fixed up the subject, please read how to properly send a v2
* I removed the changelog, it should be below the ---

-- Sebastian

>  drivers/power/supply/power_supply_hwmon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/power_supply_hwmon.c 
> b/drivers/power/supply/power_supply_hwmon.c
> index 75cf861ba492..7c8296ea0c34 100644
> --- a/drivers/power/supply/power_supply_hwmon.c
> +++ b/drivers/power/supply/power_supply_hwmon.c
> @@ -304,7 +304,7 @@ int power_supply_add_hwmon_sysfs(struct power_supply *psy)
>   goto error;
>   }
>  
> - ret = devm_add_action(dev, power_supply_hwmon_bitmap_free,
> + ret = devm_add_action_or_reset(dev, power_supply_hwmon_bitmap_free,
> psyhw->props);
>   if (ret)
>   goto error;
> -- 
> 2.17.1
> 


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

[Sebastian Reichel]

Hi,

On Sat, May 02, 2020 at 04:10:56PM -0500, wu000...@umn.edu wrote:
> From: Qiushi Wu 
> 
> 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 
> ---

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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