Bugzilla – Bug 1226783
VUL-0: CVE-2024-38558: kernel: net: openvswitch: fix overwriting ct original tuple for ICMPv6
Last modified: 2024-07-12 16:34:13 UTC
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix overwriting ct original tuple for ICMPv6 OVS_PACKET_CMD_EXECUTE has 3 main attributes: - OVS_PACKET_ATTR_KEY - Packet metadata in a netlink format. - OVS_PACKET_ATTR_PACKET - Binary packet content. - OVS_PACKET_ATTR_ACTIONS - Actions to execute on the packet. OVS_PACKET_ATTR_KEY is parsed first to populate sw_flow_key structure with the metadata like conntrack state, input port, recirculation id, etc. Then the packet itself gets parsed to populate the rest of the keys from the packet headers. Whenever the packet parsing code starts parsing the ICMPv6 header, it first zeroes out fields in the key corresponding to Neighbor Discovery information even if it is not an ND packet. It is an 'ipv6.nd' field. However, the 'ipv6' is a union that shares the space between 'nd' and 'ct_orig' that holds the original tuple conntrack metadata parsed from the OVS_PACKET_ATTR_KEY. ND packets should not normally have conntrack state, so it's fine to share the space, but normal ICMPv6 Echo packets or maybe other types of ICMPv6 can have the state attached and it should not be overwritten. The issue results in all but the last 4 bytes of the destination address being wiped from the original conntrack tuple leading to incorrect packet matching and potentially executing wrong actions in case this packet recirculates within the datapath or goes back to userspace. ND fields should not be accessed in non-ND packets, so not clearing them should be fine. Executing memset() only for actual ND packets to avoid the issue. Initializing the whole thing before parsing is needed because ND packet may not contain all the options. The issue only affects the OVS_PACKET_CMD_EXECUTE path and doesn't affect packets entering OVS datapath from network interfaces, because in this case CT metadata is populated from skb after the packet is already parsed. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-38558 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-38558.mbox https://git.kernel.org/stable/c/6a51ac92bf35d34b4996d6eb67e2fe469f573b11 https://git.kernel.org/stable/c/0b532f59437f688563e9c58bdc1436fefa46e3b5 https://git.kernel.org/stable/c/5ab6aecbede080b44b8e34720ab72050bf1e6982 https://git.kernel.org/stable/c/483eb70f441e2df66ade78aa7217e6e4caadfef3 https://git.kernel.org/stable/c/9ec8b0ccadb908d92f7ee211a4eff05fd932f3f6 https://git.kernel.org/stable/c/78741b4caae1e880368cb2f5110635f3ce45ecfd https://git.kernel.org/stable/c/431e9215576d7b728f3f53a704d237a520092120 https://git.kernel.org/stable/c/d73fb8bddf89503c9fae7c42e50d44c89909aad6 https://git.kernel.org/stable/c/7c988176b6c16c516474f6fceebe0f055af5eb56 https://www.cve.org/CVERecord?id=CVE-2024-38558 https://bugzilla.redhat.com/show_bug.cgi?id=2293441