[PATCH 4.14 30/43] net: Only honor ifindex in IP_PKTINFO if non-0

[Greg Kroah-Hartman]

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

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

From: David Ahern <dsah...@gmail.com>


[ Upstream commit 2cbb4ea7de167b02ffa63e9cdfdb07a7e7094615 ]

Only allow ifindex from IP_PKTINFO to override SO_BINDTODEVICE settings
if the index is actually set in the message.

Signed-off-by: David Ahern <dsah...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/ipv4/ip_sockglue.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -258,7 +258,8 @@ int ip_cmsg_send(struct sock *sk, struct
                        src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
                        if (!ipv6_addr_v4mapped(&src_info->ipi6_addr))
                                return -EINVAL;
-                       ipc->oif = src_info->ipi6_ifindex;
+                       if (src_info->ipi6_ifindex)
+                               ipc->oif = src_info->ipi6_ifindex;
                        ipc->addr = src_info->ipi6_addr.s6_addr32[3];
                        continue;
                }
@@ -288,7 +289,8 @@ int ip_cmsg_send(struct sock *sk, struct
                        if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct 
in_pktinfo)))
                                return -EINVAL;
                        info = (struct in_pktinfo *)CMSG_DATA(cmsg);
-                       ipc->oif = info->ipi_ifindex;
+                       if (info->ipi_ifindex)
+                               ipc->oif = info->ipi_ifindex;
                        ipc->addr = info->ipi_spec_dst.s_addr;
                        break;
                }