From 1365bedd48916c4d88eee778b24a00da23e08ff0 Mon Sep 17 00:00:00 2001 From: Heyi Guo Date: Mon, 8 Jun 2015 09:24:31 +0000 Subject: [PATCH] MdeModulePkg: Fix bug of AllocatePages for large alignment DescEnd will be clipped for alignment in CoreFindFreePagesI, and it may fall below DescStart, when alignment is more than 16KB (included) and both DescStart and original DescEnd fall into a single range of such alignment. This results in a huge size (Negative number in unsigned type) for this descriptor, fulfilling the allocation requirement but failing to run ConvertPages; at last it causes occasional failure of AllocatePages. A simple comparison is added to ensure we would never get a negative number. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Heyi Guo Reviewed-by: Liming Gao Acked-by: Ard Biesheuvel git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17575 6f19259b-4bc3-4df7-8a09-765794883524 --- MdeModulePkg/Core/Dxe/Mem/Page.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem/Page.c index a92c865e17..f2efaf1278 100644 --- a/MdeModulePkg/Core/Dxe/Mem/Page.c +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c @@ -1051,6 +1051,11 @@ CoreFindFreePagesI ( DescEnd = ((DescEnd + 1) & (~(Alignment - 1))) - 1; + // Skip if DescEnd is less than DescStart after alignment clipping + if (DescEnd < DescStart) { + continue; + } + // // Compute the number of bytes we can used from this // descriptor, and see it's enough to satisfy the request -- 2.39.2