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.
Product status
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 2e1461034aef99e905a1fe5589aaf00eaea73eee
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 242531004d7de8c159f9bfadebe33fe8060b1046
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before e8fe3f07a357c39d429e02ca34f740692d88967a
6.12.58 (semver)
6.17.8 (semver)
6.18 (original_commit_for_fix)
References
git.kernel.org/...c/2e1461034aef99e905a1fe5589aaf00eaea73eee
git.kernel.org/...c/242531004d7de8c159f9bfadebe33fe8060b1046
git.kernel.org/...c/e8fe3f07a357c39d429e02ca34f740692d88967a
