[PATCH AUTOSEL 4.19 11/49] mISDN: make sure device name is NUL terminated

Sasha Levin
2019-06-08T11:45:56Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit ccfb62f27beb295103e9392462b20a6ed807d0ea ]

The user can change the device_name with the IMSETDEVNAME ioctl, but we
need to ensure that the user's name is NUL terminated. Otherwise it
could result in a buffer overflow when we copy the name back to the user
with IMGETDEVINFO ioctl.

I also changed two strcpy() calls which handle the name to strscpy().
Hopefully, there aren't any other ways to create a too long name, but
it's nice to do this as a kernel hardening measure.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/isdn/mISDN/socket.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/isdn/mISDN/socket.c b/drivers/isdn/mISDN/socket.c
index b2abc44fa5cb..a73337b74f41 100644
--- a/drivers/isdn/mISDN/socket.c
+++ b/drivers/isdn/mISDN/socket.c
@@ -394,7 +394,7 @@ data_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
memcpy(di.channelmap, dev->channelmap,
sizeof(di.channelmap));
di.nrbchan = dev->nrbchan;
- strcpy(di.name, dev_name(&dev->dev));
+ strscpy(di.name, dev_name(&dev->dev), sizeof(di.name));
if (copy_to_user((void __user *)arg, &di, sizeof(di)))
err = -EFAULT;
} else
@@ -677,7 +677,7 @@ base_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
memcpy(di.channelmap, dev->channelmap,
sizeof(di.channelmap));
di.nrbchan = dev->nrbchan;
- strcpy(di.name, dev_name(&dev->dev));
+ strscpy(di.name, dev_name(&dev->dev), sizeof(di.name));
if (copy_to_user((void __user *)arg, &di, sizeof(di)))
err = -EFAULT;
} else
@@ -691,6 +691,7 @@ base_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
err = -EFAULT;
break;
}
+ dn.name[sizeof(dn.name) - 1] = '\0';
dev = get_mdevice(dn.id);
if (dev)
err = device_rename(&dev->dev, dn.name);
--
2.20.1