5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ido Schimmel <idosch@xxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx>
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Reviewed-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230823064348.2252280-1-idosch@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
