From 30188bd7838c16a98a520db1fe9df01ffc6ed368 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Wed, 23 Aug 2023 09:43:48 +0300 Subject: rtnetlink: Reject negative ifindexes in RTM_NEWLINK Negative ifindexes are illegal, but the kernel does not validate the ifindex in the ancillary header of RTM_NEWLINK messages, resulting in the kernel generating a warning [1] when such an ifindex is specified. Fix by rejecting negative ifindexes. [1] WARNING: CPU: 0 PID: 5031 at net/core/dev.c:9593 dev_index_reserve+0x1a2/0x1c0 net/core/dev.c:9593 [...] Call Trace: register_netdevice+0x69a/0x1490 net/core/dev.c:10081 br_dev_newlink+0x27/0x110 net/bridge/br_netlink.c:1552 rtnl_newlink_create net/core/rtnetlink.c:3471 [inline] __rtnl_newlink+0x115e/0x18c0 net/core/rtnetlink.c:3688 rtnl_newlink+0x67/0xa0 net/core/rtnetlink.c:3701 rtnetlink_rcv_msg+0x439/0xd30 net/core/rtnetlink.c:6427 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2545 netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline] netlink_unicast+0x536/0x810 net/netlink/af_netlink.c:1368 netlink_sendmsg+0x93c/0xe40 net/netlink/af_netlink.c:1910 sock_sendmsg_nosec net/socket.c:728 [inline] sock_sendmsg+0xd9/0x180 net/socket.c:751 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2538 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2592 __sys_sendmsg+0x117/0x1e0 net/socket.c:2621 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 38f7b870d4a6 ("[RTNETLINK]: Link creation API") Reported-by: syzbot+5ba06978f34abb058571@syzkaller.appspotmail.com Signed-off-by: Ido Schimmel Reviewed-by: Jiri Pirko Reviewed-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230823064348.2252280-1-idosch@nvidia.com Signed-off-by: Paolo Abeni --- net/core/rtnetlink.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/core/rtnetlink.c') diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index bcebdeb59163..00c94d9622b4 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3561,6 +3561,9 @@ replay: if (ifm->ifi_index > 0) { link_specified = true; dev = __dev_get_by_index(net, ifm->ifi_index); + } else if (ifm->ifi_index < 0) { + NL_SET_ERR_MSG(extack, "ifindex can't be negative"); + return -EINVAL; } else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME]) { link_specified = true; dev = rtnl_dev_get(net, tb); -- cgit