{"id":"CVE-2022-50220","state":"PUBLISHED","title":"usbnet: Fix linkwatch use-after-free on disconnect","description":"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->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.","publishedAt":"2025-06-18T11:03:55.461Z","updatedAt":"2026-05-11T19:15:07.972Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"d2d6b530d89b0a912148018027386aa049f0a309","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"e2a521a7dcc463c5017b4426ca0804e151faeff7","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"7f77dcbc030c2faa6d8e8a594985eeb34018409e","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"8b4588b8b00b299be16a35be67b331d8fdba03f3","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"135199a2edd459d2b123144efcd7f9bcd95128e4","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"635fd8953e4309b54ca6a81bed1d4a87668694f4","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"db3b738ae5f726204876f4303c49cfdf4311403f","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"a69e617e533edddf3fa3123149900f36e0a6dc74","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/usb/usbnet.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.38","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.38","versionType":"semver"},{"version":"4.9.326","status":"unaffected","lessThanOrEqual":"4.9.*","versionType":"semver"},{"version":"4.14.291","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.256","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.211","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.137","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.61","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.18.18","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19.2","status":"unaffected","lessThanOrEqual":"5.19.*","versionType":"semver"},{"version":"6.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/usb/usbnet.c"]}],"references":["https://git.kernel.org/stable/c/d2d6b530d89b0a912148018027386aa049f0a309","https://git.kernel.org/stable/c/e2a521a7dcc463c5017b4426ca0804e151faeff7","https://git.kernel.org/stable/c/7f77dcbc030c2faa6d8e8a594985eeb34018409e","https://git.kernel.org/stable/c/8b4588b8b00b299be16a35be67b331d8fdba03f3","https://git.kernel.org/stable/c/135199a2edd459d2b123144efcd7f9bcd95128e4","https://git.kernel.org/stable/c/635fd8953e4309b54ca6a81bed1d4a87668694f4","https://git.kernel.org/stable/c/d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f","https://git.kernel.org/stable/c/db3b738ae5f726204876f4303c49cfdf4311403f","https://git.kernel.org/stable/c/a69e617e533edddf3fa3123149900f36e0a6dc74"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/50xxx/CVE-2022-50220.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-50220","state":"PUBLISHED","datePublished":"2025-06-18T11:03:55.461Z","dateUpdated":"2026-05-11T19:15:07.972Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-06-18T10:57:27.430Z"},"containers":{"cna":{"title":"usbnet: Fix linkwatch use-after-free on disconnect","descriptions":[{"lang":"en","value":"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->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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"d2d6b530d89b0a912148018027386aa049f0a309","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"e2a521a7dcc463c5017b4426ca0804e151faeff7","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"7f77dcbc030c2faa6d8e8a594985eeb34018409e","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"8b4588b8b00b299be16a35be67b331d8fdba03f3","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"135199a2edd459d2b123144efcd7f9bcd95128e4","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"635fd8953e4309b54ca6a81bed1d4a87668694f4","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"db3b738ae5f726204876f4303c49cfdf4311403f","versionType":"git"},{"version":"23f333a2bfafba80339315b724808982a9de57d9","status":"affected","lessThan":"a69e617e533edddf3fa3123149900f36e0a6dc74","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/usb/usbnet.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.38","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.38","versionType":"semver"},{"version":"4.9.326","status":"unaffected","lessThanOrEqual":"4.9.*","versionType":"semver"},{"version":"4.14.291","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.256","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.211","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.137","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.61","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.18.18","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19.2","status":"unaffected","lessThanOrEqual":"5.19.*","versionType":"semver"},{"version":"6.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/usb/usbnet.c"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T19:15:07.972Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"4.9.326"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"4.14.291"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"4.19.256"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"5.4.211"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"5.10.137"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"5.15.61"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"5.18.18"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"5.19.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"6.0"}]}]}],"x_generator":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