Reviewed-by: Andrei Warkentin <awarkentin@vmware.com>

From: devel@edk2.groups.io <devel@edk2.groups.io> on behalf of Ard Biesheuvel via groups.io <ard.biesheuvel=arm.com@groups.io>
Sent: Wednesday, June 17, 2020 10:38 AM
To: devel@edk2.groups.io <devel@edk2.groups.io>
Cc: leif@nuviainc.com <leif@nuviainc.com>; pete@akeo.ie <pete@akeo.ie>; Andrei Warkentin <awarkentin@vmware.com>; jeremy.linton@arm.com <jeremy.linton@arm.com>; Samer.El-Haj-Mahmoud@arm.com <Samer.El-Haj-Mahmoud@arm.com>; Ard Biesheuvel <ard.biesheuvel@arm.com>
Subject: [edk2-devel] [PATCH] EmbeddedPkg/NonCoherentDmaLib: avoid dereferencing bogus buffer address
 
The bounce buffering code in NonCoherentDmaLib copies data into the
bounce buffer using CopyMem(), but passes Map->HostAddress as the
source of the copy before it has been assigned its correct value.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
---
 EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c b/EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c
index 115345765435..9c8ef5bfb533 100644
--- a/EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c
+++ b/EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c
@@ -225,8 +225,7 @@ DmaMap (
     }

 

     if (Map->Operation == MapOperationBusMasterRead) {

-      CopyMem (Map->BufferAddress, (VOID *)(UINTN)Map->HostAddress,

-        *NumberOfBytes);

+      CopyMem (Map->BufferAddress, (VOID *)(UINTN)HostAddress, *NumberOfBytes);

     }

     mCpu->FlushDataCache (mCpu, (UINTN)Map->BufferAddress, AllocSize,

             EfiCpuFlushTypeWriteBack);

--
2.27.0


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