From: Ruiyu Ni <ruiyu.ni@intel.com>
Date: Tue, 15 Sep 2015 08:38:16 +0000 (+0000)
Subject: MdeModulePkg: Enhance PCI capability looking up logic to avoid hang
X-Git-Tag: edk2-stable201903~8860
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=7d9340a3f082d2af4e69058e3083d08084d6c330;p=mirror_edk2.git

MdeModulePkg: Enhance PCI capability looking up logic to avoid hang

Certain PCI device may have capability pointing to itself.
Update LocateCapabilityRegBlock() to break when detecting such loop.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18473 6f19259b-4bc3-4df7-8a09-765794883524
---

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciCommand.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciCommand.c
index 8a8b4b8fac..0bc1fbfeff 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciCommand.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciCommand.c
@@ -173,6 +173,14 @@ LocateCapabilityRegBlock (
       return EFI_SUCCESS;
     }
 
+    //
+    // Certain PCI device may incorrectly have capability pointing to itself,
+    // break to avoid dead loop.
+    //
+    if (CapabilityPtr == (UINT8) (CapabilityEntry >> 8)) {
+      break;
+    }
+
     CapabilityPtr = (UINT8) (CapabilityEntry >> 8);
   }