Add additional sanity checks to RSA verification code.

firmware/lib/vboot_common.c

Index: firmware/lib/vboot_common.c
diff --git a/firmware/lib/vboot_common.c b/firmware/lib/vboot_common.c
index 2635fe64a12910c5c8ae31e827830f81d2896c12..32bb7dc3a7ba186798ec6fda2209a42d3479ef57 100644
--- a/firmware/lib/vboot_common.c
+++ b/firmware/lib/vboot_common.c
@@ -107,12 +107,14 @@ int PublicKeyCopy(VbPublicKey* dest, const VbPublicKey* src) {
 
 RSAPublicKey* PublicKeyToRSA(const VbPublicKey* key) {
   RSAPublicKey *rsa;
+  int key_size;
 
   if (kNumAlgorithms <= key->algorithm) {
     VBDEBUG(("Invalid algorithm.\n"));
     return NULL;
   }
-  if (RSAProcessedKeySize((int)key->algorithm) != (int)key->key_size) {
+  if (!RSAProcessedKeySize((int)key->algorithm, &key_size) ||
+      key_size != (int)key->key_size) {
     VBDEBUG(("Wrong key size for algorithm\n"));
     return NULL;
   }