fix(dcd_dwc2): Incorrect handling of ZLP for OUT transfer

Author: poornadharshan13-rgb

src/common/tusb_common.h

@@ -109,20 +109,35 @@ extern void* tusb_app_phys_to_virt(void *phys_addr);
 
 // This is a backport of memset_s from c11
 TU_ATTR_ALWAYS_INLINE static inline int tu_memset_s(void *dest, size_t destsz, int ch, size_t count) {
-  // TODO may check if desst and src is not NULL
-  if ( count > destsz ) {
+  // Validate parameters
+  if (dest == NULL) {
     return -1;
   }
+
+  if (count > destsz) {
+    return -1;
+  }
+
   memset(dest, ch, count);
   return 0;
 }
 
 // This is a backport of memcpy_s from c11
 TU_ATTR_ALWAYS_INLINE static inline int tu_memcpy_s(void *dest, size_t destsz, const void *src, size_t count) {
-  // TODO may check if desst and src is not NULL
-  if ( count > destsz ) {
+  // Validate parameters
+  if (dest == NULL) {
     return -1;
   }
+
+  // For memcpy, src may be NULL only if count == 0. Reject otherwise.
+  if (src == NULL && count != 0) {
+    return -1;
+  }
+
+  if (count > destsz) {
+    return -1;
+  }
+
   memcpy(dest, src, count);
   return 0;
 }

src/portable/synopsys/dwc2/dcd_dwc2.c

@@ -805,17 +805,18 @@ static void handle_rxflvl_irq(uint8_t rhport) {
           dfifo_read_packet(dwc2, xfer->buffer, byte_count);
           xfer->buffer += byte_count;
         }
+      }
 
-        // short packet, minus remaining bytes (xfer_size)
-        if (byte_count < xfer->max_size) {
-          const dwc2_ep_tsize_t tsiz = {.value = epout->tsiz};
-          xfer->total_len -= tsiz.xfer_size;
-          if (epnum == 0) {
-            xfer->total_len -= _dcd_data.ep0_pending[TUSB_DIR_OUT];
-            _dcd_data.ep0_pending[TUSB_DIR_OUT] = 0;
-          }
+      // short packet (including ZLP when byte_count == 0), minus remaining bytes (xfer_size)
+      if (byte_count < xfer->max_size) {
+        const dwc2_ep_tsize_t tsiz = {.value = epout->tsiz};
+        xfer->total_len -= tsiz.xfer_size;
+        if (epnum == 0) {
+          xfer->total_len -= _dcd_data.ep0_pending[TUSB_DIR_OUT];
+          _dcd_data.ep0_pending[TUSB_DIR_OUT] = 0;
         }
       }
+
       break;
     }