In the Linux kernel, the following vulnerability has been resolved:

net: mctp: Don't access ifa_index when missing

In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but
only when the struct ifaddrmsg is provided. Otherwise it will be
comparing to uninitialised memory - reproducible in the syzkaller case from
dhcpd, or busybox "ip addr show".

The kernel MCTP implementation has always filtered by ifa_index, so
existing userspace programs expecting to dump MCTP addresses must
already be passing a valid ifa_index value (either 0 or a real index).

BUG: KMSAN: uninit-value in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
 mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
 rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380
 rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824
 netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309

https://git.kernel.org/stable/c/24fa213dffa470166ec014f979f36c6ff44afb45

https://git.kernel.org/stable/c/acab78ae12c7fefb4f3bfe22e00770a5faa42724

https://git.kernel.org/stable/c/d4d1561d17eb72908e4489c0900d96e0484fac20

https://git.kernel.org/stable/c/f11cf946c0a92c560a890d68e4775723353599e1