Re: [PATCH] OvmfPkg/PlatformInitLib: Fix integrity checking failed of NvVarStore in some cases

["Yao, Jiewen" <jiewen.yao@intel.com>]

Hey
Good catch!

I think we need handle below valid cases:
1. VAR_HEADER_VALID_ONLY (0x7F) <-- Header added (*)
2. VAR_ADDED (0x3F) <-- Header + data added
3. VAR_ADDED & VAR_IN_DELETED_TRANSITION (0x3E) <-- marked as deleted, but still valid, before new data is added. (*)
4. VAR_ADDED & VAR_IN_DELETED_TRANSITION & VAR_DELETED (0x3C) <-- deleted, after new data is added.
5. VAR_ADDED & VAR_DELETED (0x3D) <-- deleted directly, without new data.
(*) means to support surprise shutdown.


For the patch:
>        if (!((VariableHeader->State == VAR_IN_DELETED_TRANSITION) ||
>              (VariableHeader->State == VAR_DELETED) ||
>              (VariableHeader->State == VAR_HEADER_VALID_ONLY) ||
> -            (VariableHeader->State == VAR_ADDED)))
> +            (VariableHeader->State == VAR_ADDED) ||
> +            (VariableHeader->State == (VAR_ADDED & VAR_DELETED)) ||
> +            (VariableHeader->State == (VAR_ADDED & VAR_IN_DELETED_TRANSITION & VAR_DELETED))))

I think:
A. If we allow (VAR_HEADER_VALID_ONLY), then we support surprise shutdown, we need also allow (VAR_ADDED & VAR_IN_DELETED_TRANSITION). It should be added as well.
B. The (VAR_IN_DELETED_TRANSITION) and (VAR_DELETED) are invalid state. They should be removed.
 
Would you please double check?




> -----Original Message-----
> From: Lee, Chun-Yi <joeyli.kernel@gmail.com>
> Sent: Tuesday, December 13, 2022 11:55 PM
> To: devel@edk2.groups.io
> Cc: Xu, Min M <min.m.xu@intel.com>; Gerd Hoffmann
> <kraxel@redhat.com>; Yao, Jiewen <jiewen.yao@intel.com>; Tom Lendacky
> <thomas.lendacky@amd.com>; James Bottomley <jejb@linux.ibm.com>;
> Aktas, Erdem <erdemaktas@google.com>; Lee, Chun-Yi <jlee@suse.com>
> Subject: [PATCH] OvmfPkg/PlatformInitLib: Fix integrity checking failed of
> NvVarStore in some cases
> 
> In the commit 4f173db8b4 "OvmfPkg/PlatformInitLib: Add functions for
> EmuVariableNvStore"
> , it introduced a PlatformValidateNvVarStore() function for checking the
> integrity of NvVarStore.
> 
> In some cases when the VariableHeader->StartId is VARIABLE_DATA, the
> VariableHeader->State
> is not just one of the four primary states: VAR_IN_DELETED_TRANSITION,
> VAR_DELETED,
> VAR_HEADER_VALID_ONLY, VAR_ADDED. The state may combined two or
> three
> states, e.g.
>     0x3C = (VAR_IN_DELETED_TRANSITION & VAR_ADDED) & VAR_DELETED
> or
>     0x3D = VAR_ADDED & VAR_DELETED
> 
> When the variable store has those variables, then system booting/rebooting
> will
> hangs in a ASSERT:
> 
> NvVarStore Variable header State was invalid.
> ASSERT
> /mnt/working/source_code-
> git/edk2/OvmfPkg/Library/PlatformInitLib/Platform.c(819):
> ((BOOLEAN)(0==1))
> 
> Adding more log to UpdateVariable() and PlatformValidateNvVarStore(), we
> can see there have some variables have 0x3C or 0x3D state in store.
> e.g.
> 
> UpdateVariable(), VariableName=BootOrder
> L1871, State=0000003F			<-- VAR_ADDED
> State &= VAR_DELETED=0000003D
> FlushHobVariableToFlash(), VariableName=BootOrder
> ...
> UpdateVariable(), VariableName=InitialAttemptOrder
> L1977, State=0000003F
> State &= VAR_IN_DELETED_TRANSITION=0000003E
> L2376, State=0000003E
> State &= VAR_DELETED=0000003C
> FlushHobVariableToFlash(), VariableName=InitialAttemptOrder
> ...
> UpdateVariable(), VariableName=ConIn
> L1977, State=0000003F
> State &= VAR_IN_DELETED_TRANSITION=0000003E
> L2376, State=0000003E
> State &= VAR_DELETED=0000003C
> FlushHobVariableToFlash(), VariableName=ConIn
> ...
> 
> So, only allowing the four primary states is not enough. This patch adds
> two more combined states to the valid states list:
> 
>     (VAR_IN_DELETED_TRANSITION & VAR_ADDED) & VAR_DELETED = 0x3c
> 
>     VAR_ADDED & VAR_DELETED = 0x3d
> 
> Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> ---
>  OvmfPkg/Library/PlatformInitLib/Platform.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/OvmfPkg/Library/PlatformInitLib/Platform.c
> b/OvmfPkg/Library/PlatformInitLib/Platform.c
> index 77f22de046..2af4cefd10 100644
> --- a/OvmfPkg/Library/PlatformInitLib/Platform.c
> +++ b/OvmfPkg/Library/PlatformInitLib/Platform.c
> @@ -705,7 +705,9 @@ PlatformValidateNvVarStore (
>        if (!((VariableHeader->State == VAR_IN_DELETED_TRANSITION) ||
>              (VariableHeader->State == VAR_DELETED) ||
>              (VariableHeader->State == VAR_HEADER_VALID_ONLY) ||
> -            (VariableHeader->State == VAR_ADDED)))
> +            (VariableHeader->State == VAR_ADDED) ||
> +            (VariableHeader->State == (VAR_ADDED & VAR_DELETED)) ||
> +            (VariableHeader->State == (VAR_ADDED &
> VAR_IN_DELETED_TRANSITION & VAR_DELETED))))
>        {
>          DEBUG ((DEBUG_ERROR, "NvVarStore Variable header State was
> invalid.\n"));
>          return FALSE;
> --
> 2.35.3