Reviewed-by: Marvin Häuser <mhaeu...@posteo.de>
> On 2. Feb 2023, at 11:21, Savva Mitrofanov <savva...@gmail.com> wrote:
>
> Corrects multiplication overflow check code and adds additional check
> for emptiness of number of blocks and block number
>
> Cc: Marvin Häuser <mhaeu...@posteo.de>
> Cc: Pedro Falcato <pedro.falc...@gmail.com>
> Cc: Vitaly Cheptsov <vit9...@protonmail.com>
> Fixes: d9ceedca6c8f ("Ext4Pkg: Add Ext4Dxe driver.")
> Signed-off-by: Savva Mitrofanov <savva...@gmail.com>
> ---
> Features/Ext4Pkg/Ext4Pkg.dsc | 2 +-
> Features/Ext4Pkg/Ext4Dxe/DiskUtil.c | 18 ++++++++++++++----
> Features/Ext4Pkg/Ext4Dxe/Extents.c | 15 ++++++++++++---
> 3 files changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/Features/Ext4Pkg/Ext4Pkg.dsc b/Features/Ext4Pkg/Ext4Pkg.dsc
> index 59bc327ebf6e..621c63eaf92d 100644
> --- a/Features/Ext4Pkg/Ext4Pkg.dsc
> +++ b/Features/Ext4Pkg/Ext4Pkg.dsc
> @@ -46,7 +46,7 @@
> DevicePathLib|MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf
>
> OrderedCollectionLib|MdePkg/Library/BaseOrderedCollectionRedBlackTreeLib/BaseOrderedCollectionRedBlackTreeLib.inf
> BaseUcs2Utf8Lib|RedfishPkg/Library/BaseUcs2Utf8Lib/BaseUcs2Utf8Lib.inf
> -
> +
> #
> # Required for stack protector support
> #
> diff --git a/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> b/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> index 32da35f7d9f5..5df9ce5bafcf 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> @@ -54,17 +54,20 @@ Ext4ReadBlocks (
> UINT64 Offset;
> UINTN Length;
>
> + ASSERT (NumberBlocks != 0);
> + ASSERT (BlockNumber != EXT4_BLOCK_FILE_HOLE);
> +
> Offset = MultU64x32 (BlockNumber, Partition->BlockSize);
> Length = NumberBlocks * Partition->BlockSize;
>
> // Check for overflow on the block -> byte conversions.
> // Partition->BlockSize is never 0, so we don't need to check for that.
>
> - if (Offset > DivU64x32 ((UINT64)-1, Partition->BlockSize)) {
> + if (DivU64x64Remainder (Offset, BlockNumber, NULL) !=
> Partition->BlockSize) {
> return EFI_INVALID_PARAMETER;
> }
>
> - if (Length > (UINTN)-1/Partition->BlockSize) {
> + if (Length / NumberBlocks != Partition->BlockSize) {
> return EFI_INVALID_PARAMETER;
> }
>
> @@ -92,14 +95,21 @@ Ext4AllocAndReadBlocks (
> VOID *Buf;
> UINTN Length;
>
> + // Check that number of blocks isn't empty, because
> + // this is incorrect condition for opened partition,
> + // so we just early-exit
> + if ((NumberBlocks == 0) || (BlockNumber == EXT4_BLOCK_FILE_HOLE)) {
> + return NULL;
> + }
> +
> Length = NumberBlocks * Partition->BlockSize;
>
> - if (Length > (UINTN)-1/Partition->BlockSize) {
> + // Check for integer overflow
> + if (Length / NumberBlocks != Partition->BlockSize) {
> return NULL;
> }
>
> Buf = AllocatePool (Length);
> -
> if (Buf == NULL) {
> return NULL;
> }
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Extents.c
> b/Features/Ext4Pkg/Ext4Dxe/Extents.c
> index e1001d0a4292..99cb0f204fc2 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Extents.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/Extents.c
> @@ -237,6 +237,7 @@ Ext4GetExtent (
> EXT4_EXTENT_HEADER *ExtHeader;
> EXT4_EXTENT_INDEX *Index;
> EFI_STATUS Status;
> + EXT4_BLOCK_NR BlockNumber;
>
> Inode = File->Inode;
> Ext = NULL;
> @@ -288,7 +289,16 @@ Ext4GetExtent (
> // Therefore, we can use binary search, and it's actually the standard
> for doing so
> // (see FreeBSD).
>
> - Index = Ext4BinsearchExtentIndex (ExtHeader, LogicalBlock);
> + Index = Ext4BinsearchExtentIndex (ExtHeader, LogicalBlock);
> + BlockNumber = Ext4ExtentIdxLeafBlock (Index);
> +
> + // Check that block isn't file hole
> + if (BlockNumber == EXT4_BLOCK_FILE_HOLE) {
> + if (Buffer != NULL) {
> + FreePool (Buffer);
> + }
> + return EFI_NO_MAPPING;
> + }
>
> if (Buffer == NULL) {
> Buffer = AllocatePool (Partition->BlockSize);
> @@ -298,8 +308,7 @@ Ext4GetExtent (
> }
>
> // Read the leaf block onto the previously-allocated buffer.
> -
> - Status = Ext4ReadBlocks (Partition, Buffer, 1, Ext4ExtentIdxLeafBlock
> (Index));
> + Status = Ext4ReadBlocks (Partition, Buffer, 1, BlockNumber);
> if (EFI_ERROR (Status)) {
> FreePool (Buffer);
> return Status;
> --
> 2.39.1
>
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