{"id":"CVE-2022-50220","summary":"usbnet: Fix linkwatch use-after-free on disconnect","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nusbnet: Fix linkwatch use-after-free on disconnect\n\nusbnet uses the work usbnet_deferred_kevent() to perform tasks which may\nsleep.  On disconnect, completion of the work was originally awaited in\n-\u003endo_stop().  But in 2003, that was moved to -\u003edisconnect() by historic\ncommit \"[PATCH] USB: usbnet, prevent exotic rtnl deadlock\":\n\n  https://git.kernel.org/tglx/history/c/0f138bbfd83c\n\nThe change was made because back then, the kernel's workqueue\nimplementation did not allow waiting for a single work.  One had to wait\nfor completion of *all* work by calling flush_scheduled_work(), and that\ncould deadlock when waiting for usbnet_deferred_kevent() with rtnl_mutex\nheld in -\u003endo_stop().\n\nThe commit solved one problem but created another:  It causes a\nuse-after-free in USB Ethernet drivers aqc111.c, asix_devices.c,\nax88179_178a.c, ch9200.c and smsc75xx.c:\n\n* If the drivers receive a link change interrupt immediately before\n  disconnect, they raise EVENT_LINK_RESET in their (non-sleepable)\n  -\u003estatus() callback and schedule usbnet_deferred_kevent().\n* usbnet_deferred_kevent() invokes the driver's -\u003elink_reset() callback,\n  which calls netif_carrier_{on,off}().\n* That in turn schedules the work linkwatch_event().\n\nBecause usbnet_deferred_kevent() is awaited after unregister_netdev(),\nnetif_carrier_{on,off}() may operate on an unregistered netdev and\nlinkwatch_event() may run after free_netdev(), causing a use-after-free.\n\nIn 2010, usbnet was changed to only wait for a single instance of\nusbnet_deferred_kevent() instead of *all* work by commit 23f333a2bfaf\n(\"drivers/net: don't use flush_scheduled_work()\").\n\nUnfortunately the commit neglected to move the wait back to\n-\u003endo_stop().  Rectify that omission at long last.","modified":"2026-04-03T13:14:39.817207Z","published":"2025-06-18T11:03:55.461Z","related":["SUSE-SU-2025:02264-1","SUSE-SU-2025:02308-1","SUSE-SU-2025:02320-1","SUSE-SU-2025:02321-1","SUSE-SU-2025:02322-1","SUSE-SU-2025:02334-1","SUSE-SU-2025:02537-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/50xxx/CVE-2022-50220.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/135199a2edd459d2b123144efcd7f9bcd95128e4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/635fd8953e4309b54ca6a81bed1d4a87668694f4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7f77dcbc030c2faa6d8e8a594985eeb34018409e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8b4588b8b00b299be16a35be67b331d8fdba03f3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a69e617e533edddf3fa3123149900f36e0a6dc74"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d2d6b530d89b0a912148018027386aa049f0a309"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/db3b738ae5f726204876f4303c49cfdf4311403f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e2a521a7dcc463c5017b4426ca0804e151faeff7"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/50xxx/CVE-2022-50220.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2022-50220"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"23f333a2bfafba80339315b724808982a9de57d9"},{"fixed":"d2d6b530d89b0a912148018027386aa049f0a309"},{"fixed":"e2a521a7dcc463c5017b4426ca0804e151faeff7"},{"fixed":"7f77dcbc030c2faa6d8e8a594985eeb34018409e"},{"fixed":"8b4588b8b00b299be16a35be67b331d8fdba03f3"},{"fixed":"135199a2edd459d2b123144efcd7f9bcd95128e4"},{"fixed":"635fd8953e4309b54ca6a81bed1d4a87668694f4"},{"fixed":"d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f"},{"fixed":"db3b738ae5f726204876f4303c49cfdf4311403f"},{"fixed":"a69e617e533edddf3fa3123149900f36e0a6dc74"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-50220.json"}}],"schema_version":"1.7.5"}