lib/mpi: added missing NULL check

Added missing NULL check after mpi_alloc_limb_space().
Signed-off-by: NDmitry Kasatkin <dmitry.kasatkin@intel.com>
Reviewed-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NJames Morris <jmorris@namei.org>

lib/mpi/mpi-div.c

@@ -210,6 +210,8 @@ int mpi_tdiv_qr(MPI quot, MPI rem, MPI num, MPI den)
 		 * numerator would be gradually overwritten by the quotient limbs.  */
 		if (qp == np) {	/* Copy NP object to temporary space.  */
 			np = marker[markidx++] = mpi_alloc_limb_space(nsize);
+			if (!np)
+				goto nomem;
 			MPN_COPY(np, qp, nsize);
 		}
 	} else			/* Put quotient at top of remainder. */