[iot] [coverity] Fix null dereferenced issues

Fix the null dereferenced issues from converity scan results.
issue id:
  3618300:Dereference after null check
  3618364:Dereference after null check
  3618463:Dereference after null check
  3618470:Explicit null dereferenced
  3618520:Dereference after null check

Test: issue fixed by converity scan.

Change-Id: I577ed094a1f9b493de61b84827c0e1157a4fbd2f
Signed-off-by: Luo Ji <ji.luo@nxp.com>

3 files changed, 13 insertions, 5 deletions

diff --git a/lib/avb/fsl/fsl_bootctl.c b/lib/avb/fsl/fsl_bootctl.c
index 737be06250..9a57557e76 100755
--- a/lib/avb/fsl/fsl_bootctl.c
+++ b/lib/avb/fsl/fsl_bootctl.c
@@ -95,7 +95,8 @@ int get_slotvar_avb(AvbABOps *ab_ops, char *cmd, char *buffer, size_t size) {
 	AvbABSlotData *slot_data;
 	int slot;
 
-	assert(ab_ops != NULL && cmd != NULL && buffer != NULL);
+	if ((ab_ops == NULL) || (cmd == NULL) || (buffer == NULL))
+		return -1;
 
 	char *str = cmd;
 	if (!strcmp_l1("has-slot:", cmd)) {
@@ -182,7 +183,9 @@ char *select_slot(AvbABOps *ab_ops) {
 	AvbABData ab_data;
 	int curr;
 
-	assert(ab_ops != NULL);
+	if (ab_ops == NULL) {
+		return NULL;
+	}
 
 	/* load ab meta */
 	if (ab_ops->read_ab_metadata == NULL ||
diff --git a/lib/avb/fsl/utils.c b/lib/avb/fsl/utils.c
index 458ccea1a1..6416fa971e 100644
--- a/lib/avb/fsl/utils.c
+++ b/lib/avb/fsl/utils.c
@@ -14,7 +14,9 @@
 int get_margin_pos(uint64_t part_start, uint64_t part_end, unsigned long blksz,
 				margin_pos_t *margin, int64_t offset, size_t num_bytes, bool allow_partial) {
 	long off;
-	assert(margin != NULL);
+	if (margin == NULL)
+		return -1;
+
 	if (blksz == 0 || part_start > part_end)
 		return -1;
 
diff --git a/net/net.c b/net/net.c
index 6e678770fa..1123850402 100644
--- a/net/net.c
+++ b/net/net.c
@@ -215,8 +215,11 @@ static int on_bootfile(const char *name, const char *value, enum env_op op,
 	switch (op) {
 	case env_op_create:
 	case env_op_overwrite:
-		copy_filename(net_boot_file_name, value,
-			      sizeof(net_boot_file_name));
+		if (value == NULL)
+			return -1;
+		else
+			copy_filename(net_boot_file_name, value,
+				      sizeof(net_boot_file_name));
 		break;
 	default:
 		break;