MdeModulePkg: UsbNetwork: fix Ethernet functional descriptor processing

This patch fixes wrong condition because of UINT16 value to integer promotion. NumberMcFilters is UINT16 value, so when bitwise shift operator applied to small integer type, the operation is preceded by integral promotion. This is described in MISRA-C:2004 guideline as Rule 10.5: "If the bitwise operators ~ and << are applied to an operand of underlying type unsigned char or unsigned short, the result shall be immediately cast to the underlying type of the operand." A simple fix for this issue would be the following: if ((UINT16)(UsbEthFunDescriptor.NumberMcFilters << 1) == 0) But this patch proposes to use bitwise AND operation with a proper bit mask rather than shifting to prevent similar mistakes in future. Cc: Richard Ho <richardho@ami.com> Cc: Rebecca Cran <rebecca@bsdio.com> Signed-off-by: Mike Maslenkin <mike.maslenkin@gmail.com>
coreboot · Oct 16, 2023 · e079482 · e079482
1 parent 326b9e1
commit e079482
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Showing 5 changed files with 7 additions and 5 deletions.
diff --git a/MdeModulePkg/Bus/Usb/UsbNetwork/NetworkCommon/PxeFunction.c b/MdeModulePkg/Bus/Usb/UsbNetwork/NetworkCommon/PxeFunction.c
@@ -829,7 +829,7 @@ SetFilter (
     }
 
     Nic->UsbEth->UsbEthFunDescriptor (Nic->UsbEth, &UsbEthFunDescriptor);
-    if ((UsbEthFunDescriptor.NumberMcFilters << 1) == 0) {
+    if ((UsbEthFunDescriptor.NumberMcFilters & MAC_FILTERS_MASK) == 0) {
       Nic->RxFilter |= PXE_OPFLAGS_RECEIVE_FILTER_ALL_MULTICAST;
       Nic->UsbEth->SetUsbEthPacketFilter (Nic->UsbEth, Nic->RxFilter);
     } else {

diff --git a/MdeModulePkg/Bus/Usb/UsbNetwork/UsbCdcEcm/UsbEcmFunction.c b/MdeModulePkg/Bus/Usb/UsbNetwork/UsbCdcEcm/UsbEcmFunction.c
@@ -628,7 +628,7 @@ SetUsbEthMcastFilter (
     return Status;
   }
 
-  if ((UsbEthFunDescriptor.NumberMcFilters << 1) == 0) {
+  if ((UsbEthFunDescriptor.NumberMcFilters & MAC_FILTERS_MASK) == 0) {
     return EFI_UNSUPPORTED;
   }
 

diff --git a/MdeModulePkg/Bus/Usb/UsbNetwork/UsbCdcNcm/UsbNcmFunction.c b/MdeModulePkg/Bus/Usb/UsbNetwork/UsbCdcNcm/UsbNcmFunction.c
@@ -714,7 +714,7 @@ SetUsbEthMcastFilter (
     return Status;
   }
 
-  if ((UsbEthFunDescriptor.NumberMcFilters << 1) == 0) {
+  if ((UsbEthFunDescriptor.NumberMcFilters & MAC_FILTERS_MASK) == 0) {
     return EFI_UNSUPPORTED;
   }
 

diff --git a/MdeModulePkg/Bus/Usb/UsbNetwork/UsbRndis/UsbRndisFunction.c b/MdeModulePkg/Bus/Usb/UsbNetwork/UsbRndis/UsbRndisFunction.c
@@ -661,7 +661,7 @@ SetUsbRndisMcastFilter (
     return Status;
   }
 
-  if ((UsbEthFunDescriptor.NumberMcFilters << 1) == 0) {
+  if ((UsbEthFunDescriptor.NumberMcFilters & MAC_FILTERS_MASK) == 0) {
     return EFI_UNSUPPORTED;
   }
 
@@ -856,7 +856,7 @@ RndisUndiReceiveFilter (
     }
 
     Nic->UsbEth->UsbEthFunDescriptor (Nic->UsbEth, &UsbEthFunDescriptor);
-    if ((UsbEthFunDescriptor.NumberMcFilters << 1) == 0) {
+    if ((UsbEthFunDescriptor.NumberMcFilters & MAC_FILTERS_MASK) == 0) {
       Nic->RxFilter |= PXE_OPFLAGS_RECEIVE_FILTER_ALL_MULTICAST;
       DEBUG ((DEBUG_INFO, "SetUsbEthPacketFilter Nic %lx Nic->UsbEth %lx ", Nic, Nic->UsbEth));
       Nic->UsbEth->SetUsbEthPacketFilter (Nic->UsbEth, Nic->RxFilter);

diff --git a/MdeModulePkg/Include/Protocol/UsbEthernetProtocol.h b/MdeModulePkg/Include/Protocol/UsbEthernetProtocol.h
@@ -42,6 +42,8 @@ typedef struct _EDKII_USB_ETHERNET_PROTOCOL EDKII_USB_ETHERNET_PROTOCOL;
 #define NETWORK_CONNECTED   0x01
 #define NETWORK_DISCONNECT  0x00
 
+#define MAC_FILTERS_MASK  0x7FFF
+
 // USB Header functional Descriptor
 typedef struct {
   UINT8     FunctionLength;