CVE-2022-49767

{"id": "CVE-2022-49767", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2025-05-01T15:15:59.483", "references": [{"url": "https://git.kernel.org/stable/c/0b5e6bd72b8171364616841603a70e4ba9837063", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/0e07032b4b4724b8ad1003698cb81083c1818999", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/5af16182c5639349415118e9e9aecd8355f7a08b", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/7abf40f06a76c0dff42eada10597917e9776fbd4", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/9f8554615df668e4bf83294633ee9d232b28ce45", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/ef575281b21e9a34dfae544a187c6aac2ae424a9", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p/trans_fd: always use O_NONBLOCK read/write\n\nsyzbot is reporting hung task at p9_fd_close() [1], for p9_mux_poll_stop()\n from p9_conn_destroy() from p9_fd_close() is failing to interrupt already\nstarted kernel_read() from p9_fd_read() from p9_read_work() and/or\nkernel_write() from p9_fd_write() from p9_write_work() requests.\n\nSince p9_socket_open() sets O_NONBLOCK flag, p9_mux_poll_stop() does not\nneed to interrupt kernel_read()/kernel_write(). However, since p9_fd_open()\ndoes not set O_NONBLOCK flag, but pipe blocks unless signal is pending,\np9_mux_poll_stop() needs to interrupt kernel_read()/kernel_write() when\nthe file descriptor refers to a pipe. In other words, pipe file descriptor\nneeds to be handled as if socket file descriptor.\n\nWe somehow need to interrupt kernel_read()/kernel_write() on pipes.\n\nA minimal change, which this patch is doing, is to set O_NONBLOCK flag\n from p9_fd_open(), for O_NONBLOCK flag does not affect reading/writing\nof regular files. But this approach changes O_NONBLOCK flag on userspace-\nsupplied file descriptors (which might break userspace programs), and\nO_NONBLOCK flag could be changed by userspace. It would be possible to set\nO_NONBLOCK flag every time p9_fd_read()/p9_fd_write() is invoked, but still\nremains small race window for clearing O_NONBLOCK flag.\n\nIf we don't want to manipulate O_NONBLOCK flag, we might be able to\nsurround kernel_read()/kernel_write() with set_thread_flag(TIF_SIGPENDING)\nand recalc_sigpending(). Since p9_read_work()/p9_write_work() works are\nprocessed by kernel threads which process global system_wq workqueue,\nsignals could not be delivered from remote threads when p9_mux_poll_stop()\n from p9_conn_destroy() from p9_fd_close() is called. Therefore, calling\nset_thread_flag(TIF_SIGPENDING)/recalc_sigpending() every time would be\nneeded if we count on signals for making kernel_read()/kernel_write()\nnon-blocking.\n\n[Dominique: add comment at Christian's suggestion]"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: 9p/trans_fd: syzbot reporta que la tarea se bloquea en p9_fd_close() [1], ya que p9_mux_poll_stop() de p9_conn_destroy() de p9_fd_close() no interrumpe las solicitudes kernel_read() de p9_fd_read() de p9_read_work() o kernel_write() de p9_fd_write() de p9_write_work() ya iniciadas. Dado que p9_socket_open() establece el indicador O_NONBLOCK, p9_mux_poll_stop() no necesita interrumpir kernel_read()/kernel_write(). Sin embargo, dado que p9_fd_open() no establece el indicador O_NONBLOCK, sino que bloquea la tuber\u00eda a menos que la se\u00f1al est\u00e9 pendiente, p9_mux_poll_stop() necesita interrumpir kernel_read()/kernel_write() cuando el descriptor de archivo hace referencia a una tuber\u00eda. En otras palabras, el descriptor de archivo de la tuber\u00eda debe manejarse como si fuera un descriptor de archivo de socket. De alguna manera, necesitamos interrumpir kernel_read()/kernel_write() en las tuber\u00edas. Un cambio m\u00ednimo, que este parche est\u00e1 realizando, es establecer el indicador O_NONBLOCK de p9_fd_open(), ya que el indicador O_NONBLOCK no afecta la lectura/escritura de archivos normales. Pero este enfoque cambia el indicador O_NONBLOCK en los descriptores de archivo proporcionados por el espacio de usuario (lo que podr\u00eda romper los programas del espacio de usuario), y el indicador O_NONBLOCK podr\u00eda ser cambiado por el espacio de usuario. Ser\u00eda posible establecer el indicador O_NONBLOCK cada vez que se invoca p9_fd_read()/p9_fd_write(), pero a\u00fan queda una peque\u00f1a ventana de tiempo para borrar el indicador O_NONBLOCK. Si no queremos manipular el indicador O_NONBLOCK, podr\u00edamos rodear kernel_read()/kernel_write() con set_thread_flag(TIF_SIGPENDING) y recalc_sigpending(). Dado que los trabajos de p9_read_work()/p9_write_work() son procesados por hilos del n\u00facleo que procesan la cola de trabajo global system_wq, no se pudieron enviar se\u00f1ales desde hilos remotos al llamar a p9_mux_poll_stop() de p9_conn_destroy() de p9_fd_close(). Por lo tanto, ser\u00eda necesario llamar a set_thread_flag(TIF_SIGPENDING)/recalc_sigpending() cada vez si dependemos de se\u00f1ales para que kernel_read()/kernel_write() sea no bloqueante. [Dominique: a\u00f1adir comentario a la sugerencia de Christian]"}], "lastModified": "2025-11-06T21:47:50.690", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "65416FEB-3A76-4DA9-A96A-1479EC77AFB6", "versionEndExcluding": "4.9.334"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "424802D2-E9E7-48A9-AD6F-DF2227B3D83A", "versionEndExcluding": "4.14.300", "versionStartIncluding": "4.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A5C69A12-68E2-400E-9A5A-375A673C8402", "versionEndExcluding": "4.19.267", "versionStartIncluding": "4.15"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "94D21814-3051-4860-AB06-C7880A3D4933", "versionEndExcluding": "5.4.225", "versionStartIncluding": "4.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E2152F3D-E6D3-405D-B0BE-911B8B6E2EE6", "versionEndExcluding": "5.10.156", "versionStartIncluding": "5.5"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "51BBEF3B-79F5-4D4C-ADBA-F34DA0E2465C", "versionEndExcluding": "5.15.80", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "64F9ADD1-3ADB-4D66-A00F-4A83010B05F0", "versionEndExcluding": "6.0.10", "versionStartIncluding": "5.16"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}