diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index c6df2925ebd..d6952959d72 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1515,6 +1515,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
 					if (copy_from_user(&iocts, argp,
 					     sizeof(isdn_ioctl_struct)))
 						return -EFAULT;
+					iocts.drvid[sizeof(iocts.drvid)-1] = 0;
 					if (strlen(iocts.drvid)) {
 						if ((p = strchr(iocts.drvid, ',')))
 							*p = 0;
@@ -1599,6 +1600,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
 					if (copy_from_user(&iocts, argp,
 					     sizeof(isdn_ioctl_struct)))
 						return -EFAULT;
+					iocts.drvid[sizeof(iocts.drvid)-1] = 0;
 					if (strlen(iocts.drvid)) {
 						drvidx = -1;
 						for (i = 0; i < ISDN_MAX_DRIVERS; i++)
@@ -1643,7 +1645,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
 					} else {
 						p = (char __user *) iocts.arg;
 						for (i = 0; i < 10; i++) {
-							sprintf(bname, "%s%s",
+							snprintf(bname, sizeof(bname), "%s%s",
 								strlen(dev->drv[drvidx]->msn2eaz[i]) ?
 								dev->drv[drvidx]->msn2eaz[i] : "_",
 								(i < 9) ? "," : "\0");
@@ -1673,6 +1675,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
 					char *p;
 					if (copy_from_user(&iocts, argp, sizeof(isdn_ioctl_struct)))
 						return -EFAULT;
+					iocts.drvid[sizeof(iocts.drvid)-1] = 0;
 					if (strlen(iocts.drvid)) {
 						if ((p = strchr(iocts.drvid, ',')))
 							*p = 0;