5.4-stable review patch. If anyone has any objections, please let me know.
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From: Ido Schimmel idosch@nvidia.com
commit 30188bd7838c16a98a520db1fe9df01ffc6ed368 upstream.
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: <TASK> 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 idosch@nvidia.com Reviewed-by: Jiri Pirko jiri@nvidia.com Reviewed-by: Jakub Kicinski kuba@kernel.org Link: https://lore.kernel.org/r/20230823064348.2252280-1-idosch@nvidia.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/rtnetlink.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3076,9 +3076,12 @@ replay: ifname[0] = '\0';
ifm = nlmsg_data(nlh); - if (ifm->ifi_index > 0) + if (ifm->ifi_index > 0) { dev = __dev_get_by_index(net, ifm->ifi_index); - else { + } else if (ifm->ifi_index < 0) { + NL_SET_ERR_MSG(extack, "ifindex can't be negative"); + return -EINVAL; + } else { if (ifname[0]) dev = __dev_get_by_name(net, ifname); else