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linux/net/9p
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Oleg Nesterov e8fe3f07a3 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 aaec5a95d5 ("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.

Reported-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Tested-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68a2de8f.050a0220.e29e5.0097.GAE@google.com/
Link: https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@google.com/
Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Message-ID: <20250819161013.GB11345@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
 		2025-09-19 16:34:51 +09:00
..
Kconfig net/9p/usbg: allow building as standalone module 2024-11-22 23:48:14 +09:00
Makefile net/9p/usbg: Add new usb gadget function transport 2024-09-03 09:57:08 +02:00
client.c netfs: Fix the request's work item to not require a ref 2025-05-21 14:35:20 +02:00
error.c 9p: Use hashtable.h for hash_errmap 2025-03-23 06:20:48 +09:00
mod.c net/p9: load default transports 2022-01-10 10:00:09 +09:00
protocol.c net: 9p: avoid freeing uninit memory in p9pdu_vreadf 2023-12-13 05:44:30 +09:00
protocol.h net/9p: add p9_msg_buf_size() 2022-10-05 07:05:41 +09:00
trans_common.c 9p: fix file headers 2021-11-03 17:45:04 +09:00
trans_common.h 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00
trans_fd.c 9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN 2025-09-19 16:34:51 +09:00
trans_rdma.c 9p/rdma: unmap receive dma buffer in rdma_request()/post_recv() 2023-02-24 13:42:28 +00:00
trans_usbg.c net/9p: Fix buffer overflow in USB transport layer 2025-08-23 15:34:46 +09:00
trans_virtio.c net: 9p: virtio: drop owner assignment 2024-05-22 08:31:17 -04:00
trans_xen.c 9p/xen: fix release of IRQ 2024-11-22 23:36:19 +09:00