Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull keys fixes from James Morris:
 "From David:

   - Fix mpi_powm()'s handling of a number with a zero exponent
     [CVE-2016-8650].

     Integrate my and Andrey's patches for mpi_powm() and use
     mpi_resize() instead of RESIZE_IF_NEEDED() - the latter adds a
     duplicate check into the execution path of a trivial case we
     don't normally expect to be taken.

   - Fix double free in X.509 error handling"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  mpi: Fix NULL ptr dereference in mpi_powm() [ver #3]
  X.509: Fix double free in x509_cert_parse() [ver #3]

Author: torvalds

crypto/asymmetric_keys/x509_cert_parser.c

@@ -133,7 +133,6 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
 	return cert;
 
 error_decode:
-	kfree(cert->pub->key);
 	kfree(ctx);
 error_no_ctx:
 	x509_free_certificate(cert);

lib/mpi/mpi-pow.c

@@ -64,8 +64,13 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
 	if (!esize) {
 		/* Exponent is zero, result is 1 mod MOD, i.e., 1 or 0
 		 * depending on if MOD equals 1.  */
-		rp[0] = 1;
 		res->nlimbs = (msize == 1 && mod->d[0] == 1) ? 0 : 1;
+		if (res->nlimbs) {
+			if (mpi_resize(res, 1) < 0)
+				goto enomem;
+			rp = res->d;
+			rp[0] = 1;
+		}
 		res->sign = 0;
 		goto leave;
 	}