{"cve":"CVE-2023-53798","nvd":{"published":"2025-12-09T01:16:51.470","modified":"2026-06-17T06:46:05.517","status":"Deferred","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nethtool: Fix uninitialized number of lanes\n\nIt is not possible to set the number of lanes when setting link modes\nusing the legacy IOCTL ethtool interface. Since 'struct\nethtool_link_ksettings' is not initialized in this path, drivers receive\nan uninitialized number of lanes in 'struct\nethtool_link_ksettings::lanes'.\n\nWhen this information is later queried from drivers, it results in the\nethtool code making decisions based on uninitialized memory, leading to\nthe following KMSAN splat [1]. In practice, this most likely only\nhappens with the tun driver that simply returns whatever it got in the\nset operation.\n\nAs far as I can tell, this uninitialized memory is not leaked to user\nspace thanks to the 'ethtool_ops->cap_link_lanes_supported' check in\nlinkmodes_prepare_data().\n\nFix by initializing the structure in the IOCTL path. Did not find any\nmore call sites that pass an uninitialized structure when calling\n'ethtool_ops::set_link_ksettings()'.\n\n[1]\nBUG: KMSAN: uninit-value in ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline]\nBUG: KMSAN: uninit-value in ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333\n ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline]\n ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333\n ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640\n genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline]\n genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]\n genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065\n netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577\n genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076\n netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]\n netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365\n netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942\n sock_sendmsg_nosec net/socket.c:724 [inline]\n sock_sendmsg net/socket.c:747 [inline]\n ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501\n ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555\n __sys_sendmsg net/socket.c:2584 [inline]\n __do_sys_sendmsg net/socket.c:2593 [inline]\n __se_sys_sendmsg net/socket.c:2591 [inline]\n __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nUninit was stored to memory at:\n tun_get_link_ksettings+0x37/0x60 drivers/net/tun.c:3544\n __ethtool_get_link_ksettings+0x17b/0x260 net/ethtool/ioctl.c:441\n ethnl_set_linkmodes+0xee/0x19d0 net/ethtool/linkmodes.c:327\n ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640\n genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline]\n genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]\n genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065\n netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577\n genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076\n netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]\n netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365\n netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942\n sock_sendmsg_nosec net/socket.c:724 [inline]\n sock_sendmsg net/socket.c:747 [inline]\n ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501\n ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555\n __sys_sendmsg net/socket.c:2584 [inline]\n __do_sys_sendmsg net/socket.c:2593 [inline]\n __se_sys_sendmsg net/socket.c:2591 [inline]\n __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nUninit was stored to memory at:\n tun_set_link_ksettings+0x37/0x60 drivers/net/tun.c:3553\n ethtool_set_link_ksettings+0x600/0x690 net/ethtool/ioctl.c:609\n __dev_ethtool net/ethtool/ioctl.c:3024 [inline]\n dev_ethtool+0x1db9/0x2a70 net/ethtool/ioctl.c:3078\n dev_ioctl+0xb07/0x1270 net/core/dev_ioctl.c:524\n sock_do_ioctl+0x295/0x540 net/socket.c:1213\n sock_i\n---truncated---","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/6456d80045d6de47734b1a3879c91f72af186529","https://git.kernel.org/stable/c/72808c4ab5fd01bf1214195005e15b434bf55cef","https://git.kernel.org/stable/c/942a2a0184f7bb1c1ae4bbc556559c86c054b0d2","https://git.kernel.org/stable/c/9ad685dbfe7e856bbf17a7177b64676d324d6ed7","https://git.kernel.org/stable/c/da81af0ef8092ecacd87fac3229c29e2e0ce39fd"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:16:40.427100871+00:00"},"epss":{"cve":"CVE-2023-53798","score":0.00201,"percentile":0.1003,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}