[PATCH 4.12 065/106] wireless: wext: terminate ifr name coming from userspace

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Levin, Alexander" <alexander.levin@xxxxxxxxxxx>


[ Upstream commit 98de4e0ea47d106846fc0e30ce4e644283fa7fc2 ]

ifr name is assumed to be a valid string by the kernel, but nothing
was forcing username to pass a valid string.

In turn, this would cause panics as we tried to access the string
past it's valid memory.

Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/dev_ioctl.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -423,6 +423,8 @@ int dev_ioctl(struct net *net, unsigned
 		if (copy_from_user(&iwr, arg, sizeof(iwr)))
 			return -EFAULT;
 
+		iwr.ifr_name[sizeof(iwr.ifr_name) - 1] = 0;
+
 		return wext_handle_ioctl(net, &iwr, cmd, arg);
 	}