net/packet: fix overflow in check for tp_reserve

When calculating po->tp_hdrlen + po->tp_reserve the result can overflow.

Fix by checking that tp_reserve <= INT_MAX on assign.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
BugLink: https://bugs.launchpad.net/bugs/1678009
CVE-2017-7308
(cherry picked from commit bcc5364bdcfe131e6379363f089e7b4108d35b70 linux-net)
Signed-off-by: Andy Whitcroft <apw@canonical.com>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 362e0ab4c516a356fc3d403d67f658651f5ad456..4835e5973e787ca83601bd0fdfc5142be5e3cc35 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3602,6 +3602,8 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
                        return -EBUSY;
                if (copy_from_user(&val, optval, sizeof(val)))
                        return -EFAULT;
+               if (val > INT_MAX)
+                       return -EINVAL;
                po->tp_reserve = val;
                return 0;
        }