Re: [PATCH v8 3/4] virt: sev-guest: Remove err in handle_guest_request

[Peter Gonda]

On Fri, Nov 4, 2022 at 5:01 PM Dionna Glaze <dionnaglaze@xxxxxxxxxx> wrote:
>
> The err variable may not be set in the call to snp_issue_guest_request,
> yet it is unconditionally written back to fw_err if fw_err is non-null.
> This is undefined behavior, and currently returns uninitialized kernel
> stack memory to user space.
>
> The fw_err argument is better to just pass through to
> snp_issue_guest_request, so we do that by passing along the ioctl
> argument. This removes the need for an argument to handle_guest_request.
>
> Cc: Tom Lendacky <Thomas.Lendacky@xxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Joerg Roedel <jroedel@xxxxxxx>
> Cc: Peter Gonda <pgonda@xxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Haowen Bai <baihaowen@xxxxxxxxx>
> Cc: Liam Merwick <liam.merwick@xxxxxxxxxx>
> Cc: Yang Yingliang <yangyingliang@xxxxxxxxxx>
>
> Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver")
> Signed-off-by: Dionna Glaze <dionnaglaze@xxxxxxxxxx>

Reviewed-by: Peter Gonda <pgonda@xxxxxxxxxx>