crypto: algif_skcipher - Cap recv SG list at ctx->used

commit 7cf81954 upstream.

Somewhere along the line the cap on the SG list length for receive
was lost.  This patch restores it and removes the subsequent test
which is now redundant.

Fixes: 2d97591e ("crypto: af_alg - consolidation of...")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

crypto/algif_skcipher.c

@@ -78,14 +78,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 		return PTR_ERR(areq);
 
 	/* convert iovecs of output buffers into RX SGL */
-	err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
+	err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
 	if (err)
 		goto free;
 
-	/* Process only as much RX buffers for which we have TX data */
-	if (len > ctx->used)
-		len = ctx->used;
-
 	/*
 	 * If more buffers are to be expected to be processed, process only
 	 * full block size buffers.