diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c index f0c92aa09a..3830af1ea7 100644 --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c @@ -39,6 +39,7 @@ PartitionValidMbr ( UINT32 StartingLBA; UINT32 EndingLBA; UINT32 NewEndingLBA; + UINT32 SizeInLBA; INTN Index1; INTN Index2; BOOLEAN MbrValid; @@ -51,13 +52,34 @@ PartitionValidMbr ( // MbrValid = FALSE; for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) { - if (Mbr->Partition[Index1].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) { + StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA); + SizeInLBA = UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA); + + // + // If the MBR with partition entry covering the ENTIRE disk, i.e. start at LBA0 + // with whole disk size, we treat it as an invalid MBR partition. + // + if ((StartingLBA == 0) && + (SizeInLBA == (LastLba + 1))) { + // + // Refer to the http://manpages.ubuntu.com/manpages/bionic/man8/mkudffs.8.html + // "WHOLE DISK VS PARTITION" + // Some linux ISOs may put the MBR table in the first 512 bytes for compatibility reasons with Windows. + // Linux kernel ignores MBR table if contains partition which starts at sector 0. + // Skip it because we don't have the partition check for UDF(El Torito compatible). + // It would continue to do the whole disk check in the UDF routine. + // + DEBUG ((DEBUG_INFO, "PartitionValidMbr: MBR table has partition entry covering the ENTIRE disk. Don't treat it as a valid MBR.\n")); + + return FALSE; + } + + if (Mbr->Partition[Index1].OSIndicator == 0x00 || SizeInLBA == 0) { continue; } MbrValid = TRUE; - StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA); - EndingLBA = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1; + EndingLBA = StartingLBA + SizeInLBA - 1; if (EndingLBA > LastLba) { // // Compatibility Errata: @@ -77,12 +99,15 @@ PartitionValidMbr ( } for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) { - if (Mbr->Partition[Index2].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) { + StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA); + SizeInLBA = UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA); + + if (Mbr->Partition[Index2].OSIndicator == 0x00 || SizeInLBA == 0) { continue; } - NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1; - if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) { + NewEndingLBA = StartingLBA + SizeInLBA - 1; + if (NewEndingLBA >= StartingLBA && StartingLBA <= EndingLBA) { // // This region overlaps with the Index1'th region //