[edk2-devel] [edk2-platforms][PATCH V3] Silicon/Synopsys/DesignWare: DwEmacSnpDxe: Fix bug in EmacGetDmaStatus

["wangy" <wangyzhaoz@163.com>]

From: Yang Wang <wangyzhaoz@163.com>

The EFI spec (see UEFI 2.10, 24.1.12) requires
EFI_SIMPLE_NETWORK.GetStatus() to handle NULL InterruptStatus pointers
by not reading nor clearing the interrupt status from the device.

However, EmacGetDmaStatus (part of the DwEmacSnpDxe GetStatus()
implementation) did not correctly handle NULL IrqStat, despite already
being tagged as an OPTIONAL argument. This made calling GetStatus()
with a NULL pointer (for example, the call in MnpRecycleTxBuf) either
corrupt memory or straight-up crash.

Make it EFI spec compliant, by adding proper NULL pointer checks
around RI_SET_MSK and TI_SET_MSK retrieval/clearing.

Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Ard Biesheuvel <ardb@kernel.org>

Signed-off-by: Yang Wang <wangyzhaoz@163.com>
Acked-by: Pedro Falcato <pedro.falcato@gmail.com>
Reviewed-by: Ran Wang <wangran@bosc.ac.cn>
---
 .../Drivers/DwEmacSnpDxe/EmacDxeUtil.c        | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/Silicon/Synopsys/DesignWare/Drivers/DwEmacSnpDxe/EmacDxeUtil.c b/Silicon/Synopsys/DesignWare/Drivers/DwEmacSnpDxe/EmacDxeUtil.c
index 3b982ce984..26d3ff6138 100755
--- a/Silicon/Synopsys/DesignWare/Drivers/DwEmacSnpDxe/EmacDxeUtil.c
+++ b/Silicon/Synopsys/DesignWare/Drivers/DwEmacSnpDxe/EmacDxeUtil.c
@@ -500,24 +500,30 @@ EmacGetDmaStatus (
   UINT32  ErrorBit;
   UINT32  Mask = 0;
 
+  if (IrqStat != NULL) {
+    *IrqStat = 0;
+  }
+
   DmaStatus = MmioRead32 (MacBaseAddress +
                            DW_EMAC_DMAGRP_STATUS_OFST);
   if (DmaStatus & DW_EMAC_DMAGRP_STATUS_NIS_SET_MSK) {
     Mask |= DW_EMAC_DMAGRP_STATUS_NIS_SET_MSK;
     // Rx interrupt
     if (DmaStatus & DW_EMAC_DMAGRP_STATUS_RI_SET_MSK) {
-      *IrqStat |= EFI_SIMPLE_NETWORK_RECEIVE_INTERRUPT;
-      Mask |= DW_EMAC_DMAGRP_STATUS_RI_SET_MSK;
-    } else {
-      *IrqStat &= ~EFI_SIMPLE_NETWORK_RECEIVE_INTERRUPT;
+      if (IrqStat != NULL) {
+        *IrqStat |= EFI_SIMPLE_NETWORK_RECEIVE_INTERRUPT;
+        Mask |= DW_EMAC_DMAGRP_STATUS_RI_SET_MSK;
+      }
     }
+
     // Tx interrupt
     if (DmaStatus & DW_EMAC_DMAGRP_STATUS_TI_SET_MSK) {
-      *IrqStat |= EFI_SIMPLE_NETWORK_TRANSMIT_INTERRUPT;
-      Mask |= DW_EMAC_DMAGRP_STATUS_TI_SET_MSK;
-    } else {
-      *IrqStat &= ~EFI_SIMPLE_NETWORK_TRANSMIT_INTERRUPT;
+      if (IrqStat != NULL) {
+        *IrqStat |= EFI_SIMPLE_NETWORK_TRANSMIT_INTERRUPT;
+        Mask |= DW_EMAC_DMAGRP_STATUS_TI_SET_MSK;
+      }
     }
+
     // Tx Buffer
     if (DmaStatus & DW_EMAC_DMAGRP_STATUS_TU_SET_MSK){
       Mask |= DW_EMAC_DMAGRP_STATUS_TU_SET_MSK;
-- 
2.25.1



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