From: Ard Biesheuvel Date: Fri, 30 Nov 2018 11:28:26 +0000 (+0100) Subject: ArmPkg/ArmMmuLib ARM: handle unmapped section in GetMemoryRegion() X-Git-Tag: edk2-stable201903~532 X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=36a87fec6879b4bd96de88a7234f9a98c69af8e1 ArmPkg/ArmMmuLib ARM: handle unmapped section in GetMemoryRegion() GetMemoryRegion() is used to obtain the attributes of an existing mapping, to permit permission attribute changes to be optimized away if the attributes don't actually change. The current ARM code assumes that a section mapping or a page mapping exists for any region passed into GetMemoryRegion(), but the region may be unmapped entirely, in which case the code will crash. So check if a section mapping exists before dereferencing it. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel Reviewed-by: Leif Lindholm Reviewed-by: Philippe Mathieu-Daudé --- diff --git a/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c b/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c index 12ca5b2667..3b29d33d0a 100644 --- a/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c +++ b/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c @@ -457,6 +457,9 @@ GetMemoryRegion ( // Get the section at the given index SectionDescriptor = FirstLevelTable[TableIndex]; + if (!SectionDescriptor) { + return EFI_NOT_FOUND; + } // If 'BaseAddress' belongs to the section then round it to the section boundary if (((SectionDescriptor & TT_DESCRIPTOR_SECTION_TYPE_MASK) == TT_DESCRIPTOR_SECTION_TYPE_SECTION) ||