fix chunk buffer size (#22969)

selfdrive/boardd/panda.cc

@@ -433,15 +433,15 @@ bool Panda::can_receive(std::vector<can_frame>& out_vec) {
   static uint8_t tail[CANPACKET_MAX_SIZE];
   uint8_t tail_size = 0;
   uint8_t counter = 0;
-  for (int i = 0; i < recv; i += 64) {
+  for (int i = 0; i < recv; i += USBPACKET_MAX_SIZE) {
     // Check for counter every 64 bytes (length of USB packet)
     if (counter != data[i]) {
       LOGE("CAN: MALFORMED USB RECV PACKET");
       break;
     }
     counter++;
-    uint8_t chunk_len = ((recv - i) > 64) ? 63 : (recv - i - 1); // as 1 is always reserved for counter
+    uint8_t chunk_len = ((recv - i) > USBPACKET_MAX_SIZE) ? 63 : (recv - i - 1); // as 1 is always reserved for counter
-    uint8_t chunk[CANPACKET_MAX_SIZE];
+    uint8_t chunk[USBPACKET_MAX_SIZE + CANPACKET_MAX_SIZE];
     memcpy(chunk, tail, tail_size);
     memcpy(&chunk[tail_size], &data[i+1], chunk_len);
     chunk_len += tail_size;

selfdrive/boardd/panda.h

@@ -17,6 +17,7 @@
 #define PANDA_BUS_CNT 4
 #define RECV_SIZE (0x4000U)
 #define USB_TX_SOFT_LIMIT   (0x100U)
+#define USBPACKET_MAX_SIZE  (0x40U)
 #define CANPACKET_HEAD_SIZE 5U
 #define CANPACKET_MAX_SIZE  72U
 #define CANPACKET_REJECTED  (0xC0U)