diff --git a/drivers/isdn/i4l/isdn_ppp.c b/drivers/isdn/i4l/isdn_ppp.c
index f37b8f6..8c46bae 100644
--- a/drivers/isdn/i4l/isdn_ppp.c
+++ b/drivers/isdn/i4l/isdn_ppp.c
@@ -449,14 +449,9 @@
 
 	/* uprog.len is unsigned short, so no overflow here */
 	len = uprog.len * sizeof(struct sock_filter);
-	code = kmalloc(len, GFP_KERNEL);
-	if (code == NULL)
-		return -ENOMEM;
-
-	if (copy_from_user(code, uprog.filter, len)) {
-		kfree(code);
-		return -EFAULT;
-	}
+	code = memdup_user(uprog.filter, len);
+	if (IS_ERR(code))
+		return PTR_ERR(code);
 
 	err = sk_chk_filter(code, uprog.len);
 	if (err) {
diff --git a/drivers/isdn/pcbit/drv.c b/drivers/isdn/pcbit/drv.c
index 123c1d6..1507d2e 100644
--- a/drivers/isdn/pcbit/drv.c
+++ b/drivers/isdn/pcbit/drv.c
@@ -411,14 +411,10 @@
 			return -EINVAL;
 		}
 
-		cbuf = kmalloc(len, GFP_KERNEL);
-		if (!cbuf)
-			return -ENOMEM;
+		cbuf = memdup_user(buf, len);
+		if (IS_ERR(cbuf))
+			return PTR_ERR(cbuf);
 
-		if (copy_from_user(cbuf, buf, len)) {
-			kfree(cbuf);
-			return -EFAULT;
-		}
 		memcpy_toio(dev->sh_mem, cbuf, len);
 		kfree(cbuf);
 		return len;
diff --git a/drivers/isdn/sc/ioctl.c b/drivers/isdn/sc/ioctl.c
index 1081091..43c5dc35 100644
--- a/drivers/isdn/sc/ioctl.c
+++ b/drivers/isdn/sc/ioctl.c
@@ -215,19 +215,13 @@
 		pr_debug("%s: DCBIOSETSPID: ioctl received\n",
 				sc_adapter[card]->devicename);
 
-		spid = kmalloc(SCIOC_SPIDSIZE, GFP_KERNEL);
-		if(!spid) {
-			kfree(rcvmsg);
-			return -ENOMEM;
-		}
-
 		/*
 		 * Get the spid from user space
 		 */
-		if (copy_from_user(spid, data->dataptr, SCIOC_SPIDSIZE)) {
+		spid = memdup_user(data->dataptr, SCIOC_SPIDSIZE);
+		if (IS_ERR(spid)) {
 			kfree(rcvmsg);
-			kfree(spid);
-			return -EFAULT;
+			return PTR_ERR(spid);
 		}
 
 		pr_debug("%s: SCIOCSETSPID: setting channel %d spid to %s\n", 
@@ -296,18 +290,13 @@
 		pr_debug("%s: SCIOSETDN: ioctl received\n",
 				sc_adapter[card]->devicename);
 
-		dn = kmalloc(SCIOC_DNSIZE, GFP_KERNEL);
-		if (!dn) {
-			kfree(rcvmsg);
-			return -ENOMEM;
-		}
 		/*
 		 * Get the spid from user space
 		 */
-		if (copy_from_user(dn, data->dataptr, SCIOC_DNSIZE)) {
+		dn = memdup_user(data->dataptr, SCIOC_DNSIZE);
+		if (IS_ERR(dn)) {
 			kfree(rcvmsg);
-			kfree(dn);
-			return -EFAULT;
+			return PTR_ERR(dn);
 		}
 
 		pr_debug("%s: SCIOCSETDN: setting channel %d dn to %s\n",