[ndctl PATCH v2 1/2] libndctl: check return value of ndctl_pfn_get_namespace

[Zhiqiang Liu <liuzhiqiang26@huawei.com>]

Recently, we use Coverity to analysis the ndctl package,
one kind of NULL_RETURNS issue is reported as follows,
pfn_clear_badblocks():
	CID 11690495: (NULL_RETURNS)
    1429. dereference: Dereferencing a pointer that might be "NULL" "ndns" when calling "ndctl_namespace_disable_safe".
dax_clear_badblocks():
	CID 11690504: (NULL_RETURNS)
    1405. dereference: Dereferencing a pointer that might be "NULL" "ndns" when calling "ndctl_namespace_disable_safe".
util_pfn_badblocks_to_json():
	CID 11690524: (NULL_RETURNS)
    812. dereference: Dereferencing a pointer that might be "NULL" "ndns" when calling "util_namespace_badblocks_to_json".

ndctl_pfn_get_namespace() may return NULL, so callers
should check return value of it. Otherwise, it may
cause access NULL pointer problem.

Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
---
v1->v2: add coverity report info as suggested by Alison

 ndctl/namespace.c | 18 ++++++++++++++----
 test/libndctl.c   |  4 ++--
 util/json.c       |  2 ++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index 0c8df9f..21089d7 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -1417,11 +1417,16 @@ static int nstype_clear_badblocks(struct ndctl_namespace *ndns,

 static int dax_clear_badblocks(struct ndctl_dax *dax)
 {
-	struct ndctl_namespace *ndns = ndctl_dax_get_namespace(dax);
-	const char *devname = ndctl_dax_get_devname(dax);
+	struct ndctl_namespace *ndns;
+	const char *devname;
 	unsigned long long begin, size;
 	int rc;

+	ndns = ndctl_dax_get_namespace(dax);
+	if (!ndns)
+		return -ENXIO;
+
+	devname = ndctl_dax_get_devname(dax);
 	begin = ndctl_dax_get_resource(dax);
 	if (begin == ULLONG_MAX)
 		return -ENXIO;
@@ -1441,11 +1446,16 @@ static int dax_clear_badblocks(struct ndctl_dax *dax)

 static int pfn_clear_badblocks(struct ndctl_pfn *pfn)
 {
-	struct ndctl_namespace *ndns = ndctl_pfn_get_namespace(pfn);
-	const char *devname = ndctl_pfn_get_devname(pfn);
+	struct ndctl_namespace *ndns;
+	const char *devname;
 	unsigned long long begin, size;
 	int rc;

+	ndns = ndctl_pfn_get_namespace(pfn);
+	if (!ndns)
+		return -ENXIO;
+
+	devname = ndctl_pfn_get_devname(pfn);
 	begin = ndctl_pfn_get_resource(pfn);
 	if (begin == ULLONG_MAX)
 		return -ENXIO;
diff --git a/test/libndctl.c b/test/libndctl.c
index 24d72b3..05e5ff2 100644
--- a/test/libndctl.c
+++ b/test/libndctl.c
@@ -1275,7 +1275,7 @@ static int check_pfn_autodetect(struct ndctl_bus *bus,
 		if (!ndctl_pfn_is_enabled(pfn))
 			continue;
 		pfn_ndns = ndctl_pfn_get_namespace(pfn);
-		if (strcmp(ndctl_namespace_get_devname(pfn_ndns), devname) != 0)
+		if (!pfn_ndns || strcmp(ndctl_namespace_get_devname(pfn_ndns), devname) != 0)
 			continue;
 		fprintf(stderr, "%s: pfn_ndns: %p ndns: %p\n", __func__,
 				pfn_ndns, ndns);
@@ -1372,7 +1372,7 @@ static int check_dax_autodetect(struct ndctl_bus *bus,
 		if (!ndctl_dax_is_enabled(dax))
 			continue;
 		dax_ndns = ndctl_dax_get_namespace(dax);
-		if (strcmp(ndctl_namespace_get_devname(dax_ndns), devname) != 0)
+		if (!dax_ndns || strcmp(ndctl_namespace_get_devname(dax_ndns), devname) != 0)
 			continue;
 		fprintf(stderr, "%s: dax_ndns: %p ndns: %p\n", __func__,
 				dax_ndns, ndns);
diff --git a/util/json.c b/util/json.c
index ca0167b..249f021 100644
--- a/util/json.c
+++ b/util/json.c
@@ -1002,6 +1002,8 @@ static struct json_object *util_pfn_badblocks_to_json(struct ndctl_pfn *pfn,
 	pfn_begin = ndctl_pfn_get_resource(pfn);
 	if (pfn_begin == ULLONG_MAX) {
 		struct ndctl_namespace *ndns = ndctl_pfn_get_namespace(pfn);
+		if (!ndns)
+			return NULL;

 		return util_namespace_badblocks_to_json(ndns, bb_count, flags);
 	}
-- 
2.23.0