CVE-2025-40305

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN

p9_read_work() doesn't set Rworksched and doesn't do schedule_work(m->rq)

if list_empty(&m->req_list).

However, if the pipe is full, we need to read more data and this used to

work prior to commit aaec5a95d59615 ("pipe_read: don't wake up the writer

if the pipe is still full").

p9_read_work() does p9_fd_read() -> ... -> anon_pipe_read() which (before

the commit above) triggered the unnecessary wakeup. This wakeup calls

p9_pollwake() which kicks p9_poll_workfn() -> p9_poll_mux(), p9_poll_mux()

will notice EPOLLIN and schedule_work(&m->rq).

This no longer happens after the optimization above, change p9_fd_request()

to use p9_poll_mux() instead of only checking for EPOLLOUT.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References