1 files changed, 15 insertions, 9 deletions

diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 6b09f6983ac0..d492a23df99c 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -183,27 +183,33 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len,
 /*
  * Verify the signature on a module.
  */
-int mod_verify_sig(const void *mod, unsigned long modlen,
-                   const void *sig, unsigned long siglen)
+int mod_verify_sig(const void *mod, unsigned long *_modlen)
 {
         struct public_key_signature *pks;
         struct module_signature ms;
         struct key *key;
-        size_t sig_len;
+        const void *sig;
+        size_t modlen = *_modlen, sig_len;
         int ret;
 
-        pr_devel("==>%s(,%lu,,%lu,)\n", __func__, modlen, siglen);
+        pr_devel("==>%s(,%lu)\n", __func__, modlen);
 
-        if (siglen <= sizeof(ms))
+        if (modlen <= sizeof(ms))
                 return -EBADMSG;
 
-        memcpy(&ms, sig + (siglen - sizeof(ms)), sizeof(ms));
-        siglen -= sizeof(ms);
+        memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
+        modlen -= sizeof(ms);
 
         sig_len = be32_to_cpu(ms.sig_len);
-        if (sig_len >= siglen ||
-            siglen - sig_len != (size_t)ms.signer_len + ms.key_id_len)
+        if (sig_len >= modlen)
                 return -EBADMSG;
+        modlen -= sig_len;
+        if ((size_t)ms.signer_len + ms.key_id_len >= modlen)
+                return -EBADMSG;
+        modlen -= (size_t)ms.signer_len + ms.key_id_len;
+
+        *_modlen = modlen;
+        sig = mod + modlen;
 
         /* For the moment, only support RSA and X.509 identifiers */
         if (ms.algo != PKEY_ALGO_RSA ||