Fix coverity defects: CID 147707

coverity scan CID:147707, Type:Double free.

Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: cao.xuewen <cao.xuewen@zte.com.cn>
Closes #5097

lib/libshare/smb.c

@@ -72,7 +72,7 @@ smb_retrieve_shares(void)
 {
 	int rc = SA_OK;
 	char file_path[PATH_MAX], line[512], *token, *key, *value;
-	char *dup_value, *path = NULL, *comment = NULL, *name = NULL;
+	char *dup_value = NULL, *path = NULL, *comment = NULL, *name = NULL;
 	char *guest_ok = NULL;
 	DIR *shares_dir;
 	FILE *share_file_fp = NULL;
@@ -136,12 +136,19 @@ smb_retrieve_shares(void)
 				goto out;
 			}
 
-			if (strcmp(key, "path") == 0)
+			if (strcmp(key, "path") == 0) {
+				free(path);
 				path = dup_value;
-			if (strcmp(key, "comment") == 0)
+			} else if (strcmp(key, "comment") == 0) {
+				free(comment);
 				comment = dup_value;
-			if (strcmp(key, "guest_ok") == 0)
+			} else if (strcmp(key, "guest_ok") == 0) {
+				free(guest_ok);
 				guest_ok = dup_value;
+			} else
+				free(dup_value);
+
+			dup_value = NULL;
 
 			if (path == NULL || comment == NULL || guest_ok == NULL)
 				continue; /* Incomplete share definition */
@@ -153,39 +160,45 @@ smb_retrieve_shares(void)
 					goto out;
 				}
 
-				strncpy(shares->name, name,
-					sizeof (shares->name));
-				shares->name [sizeof (shares->name) - 1] = '\0';
+				(void) strlcpy(shares->name, name,
+				    sizeof (shares->name));
 
-				strncpy(shares->path, path,
+				(void) strlcpy(shares->path, path,
 				    sizeof (shares->path));
-				shares->path [sizeof (shares->path) - 1] = '\0';
 
-				strncpy(shares->comment, comment,
+				(void) strlcpy(shares->comment, comment,
 				    sizeof (shares->comment));
-				shares->comment[sizeof (shares->comment)-1] =
-				    '\0';
 
 				shares->guest_ok = atoi(guest_ok);
 
 				shares->next = new_shares;
 				new_shares = shares;
 
-				name = NULL;
+				free(path);
+				free(comment);
+				free(guest_ok);
+
 				path = NULL;
 				comment = NULL;
 				guest_ok = NULL;
 			}
 		}
 
 out:
-		if (share_file_fp != NULL)
+		if (share_file_fp != NULL) {
 			fclose(share_file_fp);
+			share_file_fp = NULL;
+		}
 
 		free(name);
 		free(path);
 		free(comment);
 		free(guest_ok);
+
+		name = NULL;
+		path = NULL;
+		comment = NULL;
+		guest_ok = NULL;
 	}
 	closedir(shares_dir);