Fix crash in NamedPipeCommands.cpp caused by stack-buffer-underflow (#…

…36465)

* Fix stack-buffer-underflow in NamedPipeCommands.cpp

* Update NamedPipeCommands.cpp

examples/platform/linux/NamedPipeCommands.cpp

@@ -81,12 +81,15 @@ void * NamedPipeCommands::EventCommandListenerTask(void * arg)
             break;
         }
 
-        ssize_t readBytes      = read(fd, readbuf, kChipEventCmdBufSize);
-        readbuf[readBytes - 1] = '\0';
-        ChipLogProgress(NotSpecified, "Received payload: \"%s\"", readbuf);
+        ssize_t readBytes = read(fd, readbuf, kChipEventCmdBufSize);
+        if (readBytes > 0)
+        {
+            readbuf[readBytes - 1] = '\0';
+            ChipLogProgress(NotSpecified, "Received payload: \"%s\"", readbuf);
 
-        // Process the received command request from event fifo
-        self->mDelegate->OnEventCommandReceived(readbuf);
+            // Process the received command request from event fifo
+            self->mDelegate->OnEventCommandReceived(readbuf);
+        }
 
         close(fd);
     }