crypto: ccp: Reject SEV commands with mismatching command buffer
WARN on and reject SEV commands that provide a valid data pointer, but do
not have a known, non-zero length. And conversely, reject commands that
take a command buffer but none is provided (data is null).
Aside from sanity checking input, disallowing a non-null pointer without
a non-zero size will allow a future patch to cleanly handle vmalloc'd
data by copying the data to an internal __pa() friendly buffer.
Note, this also effectively prevents callers from using commands that
have a non-zero length and are not known to the kernel. This is not an
explicit goal, but arguably the side effect is a good thing from the
kernel's perspective.
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20210406224952.4177376-4-seanjc@google.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>