[PATCH v1 0/2] Fix memory leak and move to modern scope based rollback

[PATCH v1 0/2] Fix memory leak and move to modern scope based rollback

[Michal Wilczynski]

In acpi_nfit_init_interleave_set() there is a memory leak + improper use
of devm_*() family of functions for local memory allocations. This patch
series provides two commits - one is meant as a bug fix, and could
potentially be backported, and the other one improves old style rollback
with scope based, similar to C++ RAII [1].

Link: https://lwn.net/Articles/934679/ [1]

Michal Wilczynski (2):
  ACPI: NFIT: Fix memory leak, and local use of devm_*()
  ACPI: NFIT: Use modern scope based rollback

 drivers/acpi/nfit/core.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

-- 
2.41.0

[PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of devm_*()

[Michal Wilczynski]

devm_*() family of functions purpose is managing memory attached to a
device. So in general it should only be used for allocations that should
last for the whole lifecycle of the device. This is not the case for
acpi_nfit_init_interleave_set(). There are two allocations that are only
used locally in this function. What's more - if the function exits on
error path memory is never freed. It's still attached to dev and would
be freed on device detach, so this leak could be called a 'local leak'.

Fix this by switching from devm_kcalloc() to kcalloc(), and adding
proper rollback.

Fixes: eaf961536e16 ("libnvdimm, nfit: add interleave-set state-tracking infrastructure")
Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
 drivers/acpi/nfit/core.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index f0e6738ae3c9..78f0f855c4de 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2262,6 +2262,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 	u16 nr = ndr_desc->num_mappings;
 	struct nfit_set_info2 *info2;
 	struct nfit_set_info *info;
+	int err = 0;
 	int i;
 
 	nd_set = devm_kzalloc(dev, sizeof(*nd_set), GFP_KERNEL);
@@ -2269,13 +2270,15 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 		return -ENOMEM;
 	import_guid(&nd_set->type_guid, spa->range_guid);
 
-	info = devm_kcalloc(dev, nr, sizeof(*info), GFP_KERNEL);
+	info = kcalloc(nr, sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;
 
-	info2 = devm_kcalloc(dev, nr, sizeof(*info2), GFP_KERNEL);
-	if (!info2)
-		return -ENOMEM;
+	info2 = kcalloc(nr, sizeof(*info2), GFP_KERNEL);
+	if (!info2) {
+		err = -ENOMEM;
+		goto free_info;
+	}
 
 	for (i = 0; i < nr; i++) {
 		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
@@ -2289,7 +2292,8 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 
 		if (!memdev || !nfit_mem->dcr) {
 			dev_err(dev, "%s: failed to find DCR\n", __func__);
-			return -ENODEV;
+			err = -ENODEV;
+			goto free_info2;
 		}
 
 		map->region_offset = memdev->region_offset;
@@ -2337,10 +2341,13 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 	}
 
 	ndr_desc->nd_set = nd_set;
-	devm_kfree(dev, info);
-	devm_kfree(dev, info2);
 
-	return 0;
+free_info2:
+	kfree(info2);
+free_info:
+	kfree(info);
+
+	return err;
 }
 
 static int ars_get_cap(struct acpi_nfit_desc *acpi_desc,
-- 
2.41.0

[PATCH v1 2/2] ACPI: NFIT: Use modern scope based rollback

[Michal Wilczynski]

Change rollback in acpi_nfit_init_interleave_set() to use modern scope
based attribute __free(). This is similar to C++ RAII and is a preferred
way for handling local memory allocations.

Suggested-by: Dave Jiang <dave.jiang@intel.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
 drivers/acpi/nfit/core.c | 32 ++++++++++----------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 78f0f855c4de..079bd663495f 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2257,29 +2257,23 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 		struct nd_region_desc *ndr_desc,
 		struct acpi_nfit_system_address *spa)
 {
+	u16 nr = ndr_desc->num_mappings;
+	struct nfit_set_info2 *info2 __free(kfree) =
+		kcalloc(nr, sizeof(*info2), GFP_KERNEL);
+	struct nfit_set_info *info __free(kfree) =
+		kcalloc(nr, sizeof(*info), GFP_KERNEL);
 	struct device *dev = acpi_desc->dev;
 	struct nd_interleave_set *nd_set;
-	u16 nr = ndr_desc->num_mappings;
-	struct nfit_set_info2 *info2;
-	struct nfit_set_info *info;
-	int err = 0;
 	int i;
 
+	if (!info || !info2)
+		return -ENOMEM;
+
 	nd_set = devm_kzalloc(dev, sizeof(*nd_set), GFP_KERNEL);
 	if (!nd_set)
 		return -ENOMEM;
 	import_guid(&nd_set->type_guid, spa->range_guid);
 
-	info = kcalloc(nr, sizeof(*info), GFP_KERNEL);
-	if (!info)
-		return -ENOMEM;
-
-	info2 = kcalloc(nr, sizeof(*info2), GFP_KERNEL);
-	if (!info2) {
-		err = -ENOMEM;
-		goto free_info;
-	}
-
 	for (i = 0; i < nr; i++) {
 		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
 		struct nvdimm *nvdimm = mapping->nvdimm;
@@ -2292,8 +2286,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 
 		if (!memdev || !nfit_mem->dcr) {
 			dev_err(dev, "%s: failed to find DCR\n", __func__);
-			err = -ENODEV;
-			goto free_info2;
+			return -ENODEV;
 		}
 
 		map->region_offset = memdev->region_offset;
@@ -2342,12 +2335,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
 
 	ndr_desc->nd_set = nd_set;
 
-free_info2:
-	kfree(info2);
-free_info:
-	kfree(info);
-
-	return err;
+	return 0;
 }
 
 static int ars_get_cap(struct acpi_nfit_desc *acpi_desc,
-- 
2.41.0

Re: [PATCH v1 2/2] ACPI: NFIT: Use modern scope based rollback

[Dave Jiang]

On 9/26/23 11:45, Michal Wilczynski wrote:
> Change rollback in acpi_nfit_init_interleave_set() to use modern scope
> based attribute __free(). This is similar to C++ RAII and is a preferred
> way for handling local memory allocations.
> 
> Suggested-by: Dave Jiang <dave.jiang@intel.com>
> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/acpi/nfit/core.c | 32 ++++++++++----------------------
>  1 file changed, 10 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 78f0f855c4de..079bd663495f 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2257,29 +2257,23 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  		struct nd_region_desc *ndr_desc,
>  		struct acpi_nfit_system_address *spa)
>  {
> +	u16 nr = ndr_desc->num_mappings;
> +	struct nfit_set_info2 *info2 __free(kfree) =
> +		kcalloc(nr, sizeof(*info2), GFP_KERNEL);
> +	struct nfit_set_info *info __free(kfree) =
> +		kcalloc(nr, sizeof(*info), GFP_KERNEL);
>  	struct device *dev = acpi_desc->dev;
>  	struct nd_interleave_set *nd_set;
> -	u16 nr = ndr_desc->num_mappings;
> -	struct nfit_set_info2 *info2;
> -	struct nfit_set_info *info;
> -	int err = 0;
>  	int i;
>  
> +	if (!info || !info2)
> +		return -ENOMEM;
> +
>  	nd_set = devm_kzalloc(dev, sizeof(*nd_set), GFP_KERNEL);
>  	if (!nd_set)
>  		return -ENOMEM;
>  	import_guid(&nd_set->type_guid, spa->range_guid);
>  
> -	info = kcalloc(nr, sizeof(*info), GFP_KERNEL);
> -	if (!info)
> -		return -ENOMEM;
> -
> -	info2 = kcalloc(nr, sizeof(*info2), GFP_KERNEL);
> -	if (!info2) {
> -		err = -ENOMEM;
> -		goto free_info;
> -	}
> -
>  	for (i = 0; i < nr; i++) {
>  		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
>  		struct nvdimm *nvdimm = mapping->nvdimm;
> @@ -2292,8 +2286,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  
>  		if (!memdev || !nfit_mem->dcr) {
>  			dev_err(dev, "%s: failed to find DCR\n", __func__);
> -			err = -ENODEV;
> -			goto free_info2;
> +			return -ENODEV;
>  		}
>  
>  		map->region_offset = memdev->region_offset;
> @@ -2342,12 +2335,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  
>  	ndr_desc->nd_set = nd_set;
>  
> -free_info2:
> -	kfree(info2);
> -free_info:
> -	kfree(info);
> -
> -	return err;
> +	return 0;
>  }
>  
>  static int ars_get_cap(struct acpi_nfit_desc *acpi_desc,

Re: [PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of devm_*()

[Dave Jiang]

On 9/26/23 11:45, Michal Wilczynski wrote:
> devm_*() family of functions purpose is managing memory attached to a
> device. So in general it should only be used for allocations that should
> last for the whole lifecycle of the device. This is not the case for
> acpi_nfit_init_interleave_set(). There are two allocations that are only
> used locally in this function. What's more - if the function exits on
> error path memory is never freed. It's still attached to dev and would
> be freed on device detach, so this leak could be called a 'local leak'.
> 
> Fix this by switching from devm_kcalloc() to kcalloc(), and adding
> proper rollback.
> 
> Fixes: eaf961536e16 ("libnvdimm, nfit: add interleave-set state-tracking infrastructure")
> Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/acpi/nfit/core.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index f0e6738ae3c9..78f0f855c4de 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2262,6 +2262,7 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  	u16 nr = ndr_desc->num_mappings;
>  	struct nfit_set_info2 *info2;
>  	struct nfit_set_info *info;
> +	int err = 0;
>  	int i;
>  
>  	nd_set = devm_kzalloc(dev, sizeof(*nd_set), GFP_KERNEL);
> @@ -2269,13 +2270,15 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  		return -ENOMEM;
>  	import_guid(&nd_set->type_guid, spa->range_guid);
>  
> -	info = devm_kcalloc(dev, nr, sizeof(*info), GFP_KERNEL);
> +	info = kcalloc(nr, sizeof(*info), GFP_KERNEL);
>  	if (!info)
>  		return -ENOMEM;
>  
> -	info2 = devm_kcalloc(dev, nr, sizeof(*info2), GFP_KERNEL);
> -	if (!info2)
> -		return -ENOMEM;
> +	info2 = kcalloc(nr, sizeof(*info2), GFP_KERNEL);
> +	if (!info2) {
> +		err = -ENOMEM;
> +		goto free_info;
> +	}
>  
>  	for (i = 0; i < nr; i++) {
>  		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
> @@ -2289,7 +2292,8 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  
>  		if (!memdev || !nfit_mem->dcr) {
>  			dev_err(dev, "%s: failed to find DCR\n", __func__);
> -			return -ENODEV;
> +			err = -ENODEV;
> +			goto free_info2;
>  		}
>  
>  		map->region_offset = memdev->region_offset;
> @@ -2337,10 +2341,13 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  	}
>  
>  	ndr_desc->nd_set = nd_set;
> -	devm_kfree(dev, info);
> -	devm_kfree(dev, info2);
>  
> -	return 0;
> +free_info2:
> +	kfree(info2);
> +free_info:
> +	kfree(info);
> +
> +	return err;
>  }
>  
>  static int ars_get_cap(struct acpi_nfit_desc *acpi_desc,

Re: [PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of devm_*()

[Andy Shevchenko]

On Tue, Sep 26, 2023 at 09:45:19PM +0300, Michal Wilczynski wrote:
> devm_*() family of functions purpose is managing memory attached to a
> device. So in general it should only be used for allocations that should
> last for the whole lifecycle of the device. This is not the case for
> acpi_nfit_init_interleave_set(). There are two allocations that are only
> used locally in this function. What's more - if the function exits on
> error path memory is never freed. It's still attached to dev and would
> be freed on device detach, so this leak could be called a 'local leak'.
> 
> Fix this by switching from devm_kcalloc() to kcalloc(), and adding
> proper rollback.

LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 2/2] ACPI: NFIT: Use modern scope based rollback

[Andy Shevchenko]

On Tue, Sep 26, 2023 at 09:45:20PM +0300, Michal Wilczynski wrote:
> Change rollback in acpi_nfit_init_interleave_set() to use modern scope
> based attribute __free(). This is similar to C++ RAII and is a preferred
> way for handling local memory allocations.

LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 0/2] Fix memory leak and move to modern scope based rollback

[Wilczynski, Michal]

On 9/26/2023 8:45 PM, Michal Wilczynski wrote:
> In acpi_nfit_init_interleave_set() there is a memory leak + improper use
> of devm_*() family of functions for local memory allocations. This patch
> series provides two commits - one is meant as a bug fix, and could
> potentially be backported, and the other one improves old style rollback
> with scope based, similar to C++ RAII [1].
>
> Link: https://lwn.net/Articles/934679/ [1]
>
> Michal Wilczynski (2):
>   ACPI: NFIT: Fix memory leak, and local use of devm_*()
>   ACPI: NFIT: Use modern scope based rollback
>
>  drivers/acpi/nfit/core.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)

Hi Dan,
Do you think this patchset is fine ? Would you like me to
change anything ?

Regards,
Michał

>

RE: [PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of devm_*()

[Dan Williams]

Michal Wilczynski wrote:
> devm_*() family of functions purpose is managing memory attached to a
> device. So in general it should only be used for allocations that should
> last for the whole lifecycle of the device. This is not the case for
> acpi_nfit_init_interleave_set(). There are two allocations that are only
> used locally in this function. What's more - if the function exits on
> error path memory is never freed. It's still attached to dev and would
> be freed on device detach, so this leak could be called a 'local leak'.

This analysis is incorrect devm cleans up on driver ->probe() failure in
addition to ->remove(), and these error returns result in ->probe()
failures. No leak, i.e. this is not a fix.

The conversion to modern probe is ok if you want to resubmit that one
without this intervening change.