Re: [edk2-platforms][PATCH v3 06/11] Ext4Pkg: Corrects integer overflow check logic in DiskUtil

["Savva Mitrofanov" <savvamtr@gmail.com>]

> Why this whitespace change?

Seems code formatter just removed trailing space. If you want so, I can drop this change in v4.

> On 27 Jan 2023, at 20:24, Pedro Falcato <pedro.falcato@gmail.com> wrote:
> 
> On Fri, Jan 27, 2023 at 9:29 AM Savva Mitrofanov <savvamtr@gmail.com> wrote:
>> 
>> Corrects multiplication overflow check code
>> 
>> Cc: Marvin Häuser <mhaeuser@posteo.de>
>> Cc: Pedro Falcato <pedro.falcato@gmail.com>
>> Cc: Vitaly Cheptsov <vit9696@protonmail.com>
>> Fixes: d9ceedca6c8f ("Ext4Pkg: Add Ext4Dxe driver.")
>> Signed-off-by: Savva Mitrofanov <savvamtr@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.falcato@gmail.com>
> 
> 
> -- 
> Pedro