On Fri, Jan 27, 2023 at 9:29 AM Savva Mitrofanov <savva...@gmail.com> wrote:
>
> Corrects multiplication overflow check code
>
> 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 | 8 ++++----
> 2 files changed, 5 insertions(+), 5 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
> -
> +
Why this whitespace change?
> #
> # Required for stack protector support
> #
> diff --git a/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> b/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> index 32da35f7d9f5..c4af956da926 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/DiskUtil.c
> @@ -60,11 +60,11 @@ Ext4ReadBlocks (
> // 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 ((NumberBlocks != 0) && (DivU64x64Remainder (Offset, BlockNumber, NULL)
> != Partition->BlockSize)) {
> return EFI_INVALID_PARAMETER;
> }
>
> - if (Length > (UINTN)-1/Partition->BlockSize) {
> + if ((NumberBlocks != 0) && (Length / NumberBlocks !=
> Partition->BlockSize)) {
> return EFI_INVALID_PARAMETER;
> }
>
> @@ -94,12 +94,12 @@ Ext4AllocAndReadBlocks (
>
> Length = NumberBlocks * Partition->BlockSize;
>
> - if (Length > (UINTN)-1/Partition->BlockSize) {
> + // Check for integer overflow
> + if ((NumberBlocks != 0) && (Length / NumberBlocks !=
> Partition->BlockSize)) {
> return NULL;
> }
>
> Buf = AllocatePool (Length);
> -
> if (Buf == NULL) {
> return NULL;
> }
> --
> 2.39.0
>
I don't really like open coding this, but it does fix my buggy checks.
In the interest of not adding a new overengineered safe int library,
Reviewed-by: Pedro Falcato <pedro.falc...@gmail.com>
--
Pedro
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