[v3] Ext4Pkg: Code correctness and security improvements

[edk2-devel] [edk2-platforms][PATCH v3 02/11] Ext4Pkg: Fix incorrect checksum metadata feature check

Posted by Savva Mitrofanov 3 years ago

Missing comparison != 0 leads to broken logic condition. Also replaced
CSUM_SEED feature_incompat check with predefined macro EXT4_HAS_INCOMPAT

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/Ext4Dxe/Superblock.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Features/Ext4Pkg/Ext4Dxe/Superblock.c b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
index 5a3c7f478187..35dcf3c007c8 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Superblock.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
@@ -220,13 +220,11 @@ Ext4OpenSuperblock (
   }

 

   // At the time of writing, it's the only supported checksum.

-  if (Partition->FeaturesCompat & EXT4_FEATURE_RO_COMPAT_METADATA_CSUM &&

-      (Sb->s_checksum_type != EXT4_CHECKSUM_CRC32C))

-  {

+  if (EXT4_HAS_METADATA_CSUM (Partition) && (Sb->s_checksum_type != EXT4_CHECKSUM_CRC32C)) {

     return EFI_UNSUPPORTED;

   }

 

-  if ((Partition->FeaturesIncompat & EXT4_FEATURE_INCOMPAT_CSUM_SEED) != 0) {

+  if (EXT4_HAS_INCOMPAT (Partition, EXT4_FEATURE_INCOMPAT_CSUM_SEED)) {

     Partition->InitialSeed = Sb->s_checksum_seed;

   } else {

     Partition->InitialSeed = Ext4CalculateChecksum (Partition, Sb->s_uuid, 16, ~0U);

-- 
2.39.0



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Re: [edk2-devel] [edk2-platforms][PATCH v3 02/11] Ext4Pkg: Fix incorrect checksum metadata feature check

Posted by Marvin Häuser 3 years ago

On 27. Jan 2023, at 10:29, Savva Mitrofanov <savvamtr@gmail.com> wrote:
> 
> Missing comparison != 0 leads to broken logic condition.

The actual issue appears to be FeaturesCompat vs FeaturesRoCompat (latter is hidden by your usage of the macro). Checking for != 0 is redundant (albeit required by the code style guideline for non-functional reasons). Please confirm and update the commit message if you agree.

> Also replaced
> CSUM_SEED feature_incompat check with predefined macro EXT4_HAS_INCOMPAT
> 
> 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/Ext4Dxe/Superblock.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Superblock.c b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> index 5a3c7f478187..35dcf3c007c8 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> @@ -220,13 +220,11 @@ Ext4OpenSuperblock (
>   }
> 
>   // At the time of writing, it's the only supported checksum.
> -  if (Partition->FeaturesCompat & EXT4_FEATURE_RO_COMPAT_METADATA_CSUM &&
> -      (Sb->s_checksum_type != EXT4_CHECKSUM_CRC32C))
> -  {
> +  if (EXT4_HAS_METADATA_CSUM (Partition) && (Sb->s_checksum_type != EXT4_CHECKSUM_CRC32C)) {
>     return EFI_UNSUPPORTED;
>   }
> 
> -  if ((Partition->FeaturesIncompat & EXT4_FEATURE_INCOMPAT_CSUM_SEED) != 0) {
> +  if (EXT4_HAS_INCOMPAT (Partition, EXT4_FEATURE_INCOMPAT_CSUM_SEED)) {
>     Partition->InitialSeed = Sb->s_checksum_seed;
>   } else {
>     Partition->InitialSeed = Ext4CalculateChecksum (Partition, Sb->s_uuid, 16, ~0U);
> -- 
> 2.39.0
> 



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Re: [edk2-devel] [edk2-platforms][PATCH v3 02/11] Ext4Pkg: Fix incorrect checksum metadata feature check

Posted by Savva Mitrofanov 3 years ago

Thanks for pointing this, yes, this change actually replaces structure field from FeaturesCompat to FeaturesRoCompat. The commit message was already corrected in referenced repository fork.

> On 27 Jan 2023, at 16:02, Marvin Häuser <mhaeuser@posteo.de> wrote:
> 
> The actual issue appears to be FeaturesCompat vs FeaturesRoCompat (latter is hidden by your usage of the macro). Checking for != 0 is redundant (albeit required by the code style guideline for non-functional reasons). Please confirm and update the commit message if you agree.



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Re: [edk2-devel] [edk2-platforms][PATCH v3 02/11] Ext4Pkg: Fix incorrect checksum metadata feature check

Posted by Pedro Falcato 3 years ago

On Fri, Jan 27, 2023 at 10:02 AM Marvin Häuser <mhaeuser@posteo.de> wrote:
>
> On 27. Jan 2023, at 10:29, Savva Mitrofanov <savvamtr@gmail.com> wrote:
> >
> > Missing comparison != 0 leads to broken logic condition.
>
> The actual issue appears to be FeaturesCompat vs FeaturesRoCompat (latter is hidden by your usage of the macro). Checking for != 0 is redundant (albeit required by the code style guideline for non-functional reasons). Please confirm and update the commit message if you agree.

+1, the actual issue comes from using the wrong feature mask and not the != 0.
If we get a v4, please update, else I can rewrite it myself.

Reviewed-by: Pedro Falcato <pedro.falcato@gmail.com>

-- 
Pedro


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Re: [edk2-devel] [edk2-platforms][PATCH v3 02/11] Ext4Pkg: Fix incorrect checksum metadata feature check

Posted by Marvin Häuser 3 years ago

With the commit message changed,

Reviewed-by: Marvin Häuser <mhaeuser@posteo.de>

> On 27. Jan 2023, at 15:29, Pedro Falcato <pedro.falcato@gmail.com> wrote:
> 
> On Fri, Jan 27, 2023 at 10:02 AM Marvin Häuser <mhaeuser@posteo.de> wrote:
>> 
>>> On 27. Jan 2023, at 10:29, Savva Mitrofanov <savvamtr@gmail.com> wrote:
>>> 
>>> Missing comparison != 0 leads to broken logic condition.
>> 
>> The actual issue appears to be FeaturesCompat vs FeaturesRoCompat (latter is hidden by your usage of the macro). Checking for != 0 is redundant (albeit required by the code style guideline for non-functional reasons). Please confirm and update the commit message if you agree.
> 
> +1, the actual issue comes from using the wrong feature mask and not the != 0.
> If we get a v4, please update, else I can rewrite it myself.
> 
> Reviewed-by: Pedro Falcato <pedro.falcato@gmail.com>
> 
> -- 
> Pedro



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