isdn: avoid copying too long drvid

"cfg->drvid" comes from the user so there is a possibility they
didn't NUL terminate it properly.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/isdn/i4l/isdn_net.c b/drivers/isdn/i4l/isdn_net.c
index 1f73d7f7e024..2339d7396b9e 100644
--- a/drivers/isdn/i4l/isdn_net.c
+++ b/drivers/isdn/i4l/isdn_net.c
@@ -2756,6 +2756,9 @@ isdn_net_setcfg(isdn_net_ioctl_cfg * cfg)
                         char *c,
                         *e;
 
+                        if (strnlen(cfg->drvid, sizeof(cfg->drvid)) ==
+                                        sizeof(cfg->drvid))
+                                return -EINVAL;
                         drvidx = -1;
                         chidx = -1;
                         strcpy(drvid, cfg->drvid);