CVE-2022-49767: 9p/trans_fd: always use O_NONBLOCK read/write
Vulnerability summary
CVE-2022-49767 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 10.3% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 6 · Related 6Timeline
- 01-05-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: 9p/trans_fd: always use O_NONBLOCK read/write syzbot is reporting hung task at p9_fd_close() [1], for p9_mux_poll_stop() from p9_conn_destroy() from p9_fd_close() is failing to interrupt already started kernel_read() from p9_fd_read() from p9_read_work() and/or kernel_write() from p9_fd_write() from p9_write_work() requests. Since p9_socket_open() sets O_NONBLOCK flag, p9_mux_poll_stop() does not need to interrupt kernel_read()/kernel_write(). However, since p9_fd_open() does not set O_NONBLOCK flag, but pipe blocks unless signal is pending, p9_mux_poll_stop() needs to interrupt kernel_read()/kernel_write() when the file descriptor refers to a pipe. In other words, pipe file descriptor needs to be handled as if socket file descriptor. We somehow need to interrupt kernel_read()/kernel_write() on pipes. A minimal change, which this patch is doing, is to set O_NONBLOCK flag from p9_fd_open(), for O_NONBLOCK flag does not affect reading/writing of regular files. But this approach changes O_NONBLOCK flag on userspace- supplied file descriptors (which might break userspace programs), and O_NONBLOCK flag could be changed by userspace. It would be possible to set O_NONBLOCK flag every time p9_fd_read()/p9_fd_write() is invoked, but still remains small race window for clearing O_NONBLOCK flag. If we don't want to manipulate O_NONBLOCK flag, we might be able to surround kernel_read()/kernel_write() with set_thread_flag(TIF_SIGPENDING) and recalc_sigpending(). Since p9_read_work()/p9_write_work() works are processed by kernel threads which process global system_wq workqueue, signals could not be delivered from remote threads when p9_mux_poll_stop() from p9_conn_destroy() from p9_fd_close() is called. Therefore, calling set_thread_flag(TIF_SIGPENDING)/recalc_sigpending() every time would be needed if we count on signals for making kernel_read()/kernel_write() non-blocking. [Dominique: add comment at Christian's suggestion]
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.20%
Chance of exploitation in the next 30 days
Percentile
10%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.20% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu114 products
- linuxAll versions (No fix recorded) | < 4.15.0-206.217 | < 5.4.0-144.161 | < 5.15.0-67.74
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1151.164 | < 5.4.0-1097.105 | < 5.15.0-1031.35
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 27979bb2ff748613dba96ae66392a76fb0678527, < 0b5e6bd72b8171364616841603a70e4ba9837063 | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < 9f8554615df668e4bf83294633ee9d232b28ce45 | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < 7abf40f06a76c0dff42eada10597917e9776fbd4 | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < b1ad04da7fe4515e2ce2d5f2dcab3b5b6d45614b | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < a8e2fc8f7b41fa9d9ca5f624f4e4d34fce5b40a9 | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < 0e07032b4b4724b8ad1003698cb81083c1818999 | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < 5af16182c5639349415118e9e9aecd8355f7a08b | ≥ 27979bb2ff748613dba96ae66392a76fb0678527, < ef575281b21e9a34dfae544a187c6aac2ae424a9 | 2.6.17
- linux_kernel< 4.9.334 | ≥ 4.10, < 4.14.300 | ≥ 4.15, < 4.19.267 | ≥ 4.20, < 5.4.225 | ≥ 5.5, < 5.10.156 | ≥ 5.11, < 5.15.80 | ≥ 5.16, < 6.0.10
Debian1 product
- linux< 6.0.10-1
3 vendors · 117 products
