{"id":"CVE-2022-49767","state":"PUBLISHED","title":"9p/trans_fd: always use O_NONBLOCK read/write","description":"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]","publishedAt":"2025-05-01T14:09:06.183Z","updatedAt":"2026-05-11T19:06:23.271Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"0b5e6bd72b8171364616841603a70e4ba9837063","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"9f8554615df668e4bf83294633ee9d232b28ce45","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"7abf40f06a76c0dff42eada10597917e9776fbd4","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"0e07032b4b4724b8ad1003698cb81083c1818999","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"5af16182c5639349415118e9e9aecd8355f7a08b","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"ef575281b21e9a34dfae544a187c6aac2ae424a9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"4.9.334","status":"unaffected","lessThanOrEqual":"4.9.*","versionType":"semver"},{"version":"4.14.300","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.267","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.225","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.156","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.80","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.0.10","status":"unaffected","lessThanOrEqual":"6.0.*","versionType":"semver"},{"version":"6.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]}],"references":["https://git.kernel.org/stable/c/0b5e6bd72b8171364616841603a70e4ba9837063","https://git.kernel.org/stable/c/9f8554615df668e4bf83294633ee9d232b28ce45","https://git.kernel.org/stable/c/7abf40f06a76c0dff42eada10597917e9776fbd4","https://git.kernel.org/stable/c/b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b","https://git.kernel.org/stable/c/a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9","https://git.kernel.org/stable/c/0e07032b4b4724b8ad1003698cb81083c1818999","https://git.kernel.org/stable/c/5af16182c5639349415118e9e9aecd8355f7a08b","https://git.kernel.org/stable/c/ef575281b21e9a34dfae544a187c6aac2ae424a9"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/49xxx/CVE-2022-49767.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-49767","state":"PUBLISHED","datePublished":"2025-05-01T14:09:06.183Z","dateUpdated":"2026-05-11T19:06:23.271Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:17:33.804Z"},"containers":{"cna":{"title":"9p/trans_fd: always use O_NONBLOCK read/write","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]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"0b5e6bd72b8171364616841603a70e4ba9837063","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"9f8554615df668e4bf83294633ee9d232b28ce45","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"7abf40f06a76c0dff42eada10597917e9776fbd4","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"0e07032b4b4724b8ad1003698cb81083c1818999","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"5af16182c5639349415118e9e9aecd8355f7a08b","versionType":"git"},{"version":"27979bb2ff748613dba96ae66392a76fb0678527","status":"affected","lessThan":"ef575281b21e9a34dfae544a187c6aac2ae424a9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"4.9.334","status":"unaffected","lessThanOrEqual":"4.9.*","versionType":"semver"},{"version":"4.14.300","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.267","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.225","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.156","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.80","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.0.10","status":"unaffected","lessThanOrEqual":"6.0.*","versionType":"semver"},{"version":"6.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0b5e6bd72b8171364616841603a70e4ba9837063"},{"url":"https://git.kernel.org/stable/c/9f8554615df668e4bf83294633ee9d232b28ce45"},{"url":"https://git.kernel.org/stable/c/7abf40f06a76c0dff42eada10597917e9776fbd4"},{"url":"https://git.kernel.org/stable/c/b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b"},{"url":"https://git.kernel.org/stable/c/a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9"},{"url":"https://git.kernel.org/stable/c/0e07032b4b4724b8ad1003698cb81083c1818999"},{"url":"https://git.kernel.org/stable/c/5af16182c5639349415118e9e9aecd8355f7a08b"},{"url":"https://git.kernel.org/stable/c/ef575281b21e9a34dfae544a187c6aac2ae424a9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T19:06:23.271Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"4.9.334"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"4.14.300"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"4.19.267"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.4.225"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.10.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.15.80"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}