Re: [PATCH v2] KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel memory leak.

[Peter Gonda]

On Mon, May 16, 2022 at 8:43 AM Ashish Kalra <Ashish.Kalra@xxxxxxx> wrote:
>
> From: Ashish Kalra <ashish.kalra@xxxxxxx>
>
> For some sev ioctl interfaces, the length parameter that is passed maybe
> less than or equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data
> that PSP firmware returns. In this case, kmalloc will allocate memory
> that is the size of the input rather than the size of the data.
> Since PSP firmware doesn't fully overwrite the allocated buffer, these
> sev ioctl interface may return uninitialized kernel slab memory.
>
> Reported-by: Andy Nguyen <theflow@xxxxxxxxxx>
> Suggested-by: David Rientjes <rientjes@xxxxxxxxxx>
> Suggested-by: Peter Gonda <pgonda@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Fixes: eaf78265a4ab3 ("KVM: SVM: Move SEV code to separate file")
> Fixes: 2c07ded06427d ("KVM: SVM: add support for SEV attestation command")
> Fixes: 4cfdd47d6d95a ("KVM: SVM: Add KVM_SEV SEND_START command")
> Fixes: d3d1af85e2c75 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
> Fixes: eba04b20e4861 ("KVM: x86: Account a variety of miscellaneous allocations")
> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>

Reviewed-by: Peter Gonda <pgonda@xxxxxxxxxx>