net/appletalk: fix minor pointer leak to userspace in SIOCFINDIPDDPRT

commit 9824dfae5741275473a23a7ed5756c7b6efacc9d upstream.

Fields ->dev and ->next of struct ipddp_route may be copied to
userspace on the SIOCFINDIPDDPRT ioctl. This is only accessible
to CAP_NET_ADMIN though. Let's manually copy the relevant fields
instead of using memcpy().

BugLink: http://blog.infosectcbr.com.au/2018/09/linux-kernel-infoleaks.html
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
CVE-2018-20511
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>

Change-Id: I74f1982a5c0a14514348aaecbc351bc3249c52da
1 file changed