linux-kernel - [PATCH v2] ACPI: NFIT: Fix local use of devm

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Message-ID: <20231013085722.3031537-1-michal.wilczynski@intel.com>
Date:   Fri, 13 Oct 2023 11:57:22 +0300
From:   Michal Wilczynski <michal.wilczynski@...el.com>
To:     nvdimm@...ts.linux.dev, linux-acpi@...r.kernel.org,
        dan.j.williams@...el.com
Cc:     rafael@...nel.org, vishal.l.verma@...el.com, lenb@...nel.org,
        dave.jiang@...el.com, ira.weiny@...el.com,
        linux-kernel@...r.kernel.org,
        Michal Wilczynski <michal.wilczynski@...el.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: [PATCH v2] ACPI: NFIT: Fix local use of devm_*()

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.

Fix this by switching from devm_kcalloc() to kcalloc(), and adding
modern scope based rollback. This is similar to C++ RAII and is
preferred way for handling local memory allocations.

Reported-by: Andy Shevchenko <andy.shevchenko@...il.com>
Suggested-by: Dave Jiang <dave.jiang@...el.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@...il.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@...el.com>
---
v2:
 - removed first commit from the patchset, as the commit couldn't
   be marked as a fix
 - squashed those commits together, since the second one were
   mostly overwriting the previous one

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

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 3826f49d481b..67a844a705c4 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2257,26 +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 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 = devm_kcalloc(dev, nr, sizeof(*info), GFP_KERNEL);
-	if (!info)
-		return -ENOMEM;
-
-	info2 = devm_kcalloc(dev, nr, sizeof(*info2), GFP_KERNEL);
-	if (!info2)
-		return -ENOMEM;
-
 	for (i = 0; i < nr; i++) {
 		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
 		struct nvdimm *nvdimm = mapping->nvdimm;
@@ -2337,8 +2334,6 @@ 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;
 }
-- 
2.41.0