[PATCH] nvdimm: Replace the usage of a variable by a direct function call in nd_pfn_validate()

[Markus Elfring]

Date: Fri, 14 Apr 2023 12:01:15 +0200

The address of a data structure member was determined before
a corresponding null pointer check in the implementation of
the function “nd_pfn_validate”.

Thus avoid the risk for undefined behaviour by replacing the usage of
the local variable “parent_uuid” by a direct function call within
a later condition check.

This issue was detected by using the Coccinelle software.

Fixes: d1c6e08e7503649e4a4f3f9e700e2c05300b6379 ("libnvdimm/labels: Add uuid 
helpers")
Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 drivers/nvdimm/pfn_devs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index af7d9301520c..f14cbfa500ed 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -456,7 +456,6 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
        unsigned long align, start_pad;
        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
        struct nd_namespace_common *ndns = nd_pfn->ndns;
-       const uuid_t *parent_uuid = nd_dev_to_uuid(&ndns->dev);

        if (!pfn_sb || !ndns)
                return -ENODEV;
@@ -476,7 +475,7 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
                return -ENODEV;
        pfn_sb->checksum = cpu_to_le64(checksum);

-       if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
+       if (memcmp(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16) != 0)
                return -ENODEV;

        if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
--
2.40.0