{"id":"CVE-2022-50220","title":"usbnet: Fix linkwatch use-after-free on disconnect","summary":"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 wo…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < d2d6b530d89b0a912148018027386aa049f0a309","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < e2a521a7dcc463c5017b4426ca0804e151faeff7","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 7f77dcbc030c2faa6d8e8a594985eeb34018409e","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 8b4588b8b00b299be16a35be67b331d8fdba03f3","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 135199a2edd459d2b123144efcd7f9bcd95128e4","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 635fd8953e4309b54ca6a81bed1d4a87668694f4","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < db3b738ae5f726204876f4303c49cfdf4311403f","Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < a69e617e533edddf3fa3123149900f36e0a6dc74","Linux 2.6.38"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T20:07:05.736067Z"},"published":"2025-06-18","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:10:29.354Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2022-50220","references":[{"url":"https://git.kernel.org/stable/c/d2d6b530d89b0a912148018027386aa049f0a309"},{"url":"https://git.kernel.org/stable/c/e2a521a7dcc463c5017b4426ca0804e151faeff7"},{"url":"https://git.kernel.org/stable/c/7f77dcbc030c2faa6d8e8a594985eeb34018409e"},{"url":"https://git.kernel.org/stable/c/8b4588b8b00b299be16a35be67b331d8fdba03f3"},{"url":"https://git.kernel.org/stable/c/135199a2edd459d2b123144efcd7f9bcd95128e4"},{"url":"https://git.kernel.org/stable/c/635fd8953e4309b54ca6a81bed1d4a87668694f4"},{"url":"https://git.kernel.org/stable/c/d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f"},{"url":"https://git.kernel.org/stable/c/db3b738ae5f726204876f4303c49cfdf4311403f"},{"url":"https://git.kernel.org/stable/c/a69e617e533edddf3fa3123149900f36e0a6dc74"}],"tags":["cve.org"],"epss":0.00246,"epssPercentile":0.15955,"ingestedAt":"2026-11-05T22:38:31.705Z","slug":"CVE-2022-50220","body":"## Overview\n\nIn 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->ndo_stop().  But in 2003, that was moved to ->disconnect() 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 ->ndo_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  ->status() callback and schedule usbnet_deferred_kevent().\n* usbnet_deferred_kevent() invokes the driver's ->link_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->ndo_stop().  Rectify that omission at long last.\n\n## Affected\n\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < d2d6b530d89b0a912148018027386aa049f0a309`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < e2a521a7dcc463c5017b4426ca0804e151faeff7`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 7f77dcbc030c2faa6d8e8a594985eeb34018409e`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 8b4588b8b00b299be16a35be67b331d8fdba03f3`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 135199a2edd459d2b123144efcd7f9bcd95128e4`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < 635fd8953e4309b54ca6a81bed1d4a87668694f4`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < db3b738ae5f726204876f4303c49cfdf4311403f`\n- `Linux >= 23f333a2bfafba80339315b724808982a9de57d9 < a69e617e533edddf3fa3123149900f36e0a6dc74`\n- `Linux 2.6.38`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}