CVE-2025-68785

Description

In the Linux kernel, the following vulnerability has been resolved:net: openvswitch: fix middle attribute validation in push_nsh() actionThe push_nsh() action structure looks like this: OVS_ACTION_ATTR_PUSH_NSH(OVS_KEY_ATTR_NSH(OVS_NSH_KEY_ATTR_BASE,...))The outermost OVS_ACTION_ATTR_PUSH_NSH attribute is OKed by thenla_for_each_nested() inside __ovs_nla_copy_actions(). The innermostOVS_NSH_KEY_ATTR_BASE/MD1/MD2 are OKed by the nla_for_each_nested()inside nsh_key_put_from_nlattr(). But nothing checks if the attributein the middle is OK. We dont even check that this attribute is theOVS_KEY_ATTR_NSH. We just do a double unwrap with a pair of nla_data()calls - first time directly while calling validate_push_nsh() and thesecond time as part of the nla_for_each_nested() macro, which isntsafe, potentially causing invalid memory access if the size of thisattribute is incorrect. The failure may not be noticed duringvalidation due to larger netlink buffer, but cause trouble later duringaction execution where the buffer is allocated exactly to the size: BUG: KASAN: slab-out-of-bounds in nsh_hdr_from_nlattr+0x1dd/0x6a0 [openvswitch] Read of size 184 at addr ffff88816459a634 by task a.out/22624 CPU: 8 UID: 0 PID: 22624 6.18.0-rc7+ #115 PREEMPT(voluntary) Call Trace: dump_stack_lvl+0x51/0x70 print_address_description.constprop.0+0x2c/0x390 kasan_report+0xdd/0x110 kasan_check_range+0x35/0x1b0 __asan_memcpy+0x20/0x60 nsh_hdr_from_nlattr+0x1dd/0x6a0 [openvswitch] push_nsh+0x82/0x120 [openvswitch] do_execute_actions+0x1405/0x2840 [openvswitch] ovs_execute_actions+0xd5/0x3b0 [openvswitch] ovs_packet_cmd_execute+0x949/0xdb0 [openvswitch] genl_family_rcv_msg_doit+0x1d6/0x2b0 genl_family_rcv_msg+0x336/0x580 genl_rcv_msg+0x9f/0x130 netlink_rcv_skb+0x11f/0x370 genl_rcv+0x24/0x40 netlink_unicast+0x73e/0xaa0 netlink_sendmsg+0x744/0xbf0 __sys_sendto+0x3d6/0x450 do_syscall_64+0x79/0x2c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Lets add some checks that the attribute is properly sized and itsthe only one attribute inside the action. Technically, there is noreal reason for OVS_KEY_ATTR_NSH to be there, as we know that werepushing an NSH header already, it just creates extra nesting, butthats how uAPI works today. So, keeping as it is.

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234