6.12-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Begunkov asml.silence@gmail.com
commit 67c007d6c12da3e456c005083696c20d4498ae72 upstream.
refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 5823 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Call Trace: <TASK> io_notif_flush io_uring/notif.h:40 [inline] io_send_zc_cleanup+0x121/0x170 io_uring/net.c:1222 io_clean_op+0x58c/0x9a0 io_uring/io_uring.c:406 io_free_batch_list io_uring/io_uring.c:1429 [inline] __io_submit_flush_completions+0xc16/0xd20 io_uring/io_uring.c:1470 io_submit_flush_completions io_uring/io_uring.h:159 [inline]
Before the blamed commit, sendzc relied on io_req_msg_cleanup() to clear REQ_F_NEED_CLEANUP, so after the following snippet the request will never hit the core io_uring cleanup path.
io_notif_flush(); io_req_msg_cleanup();
The easiest fix is to null the notification. io_send_zc_cleanup() can still be called after, but it's tolerated.
Reported-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com Tested-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com Fixes: cc34d8330e036 ("io_uring/net: don't clear REQ_F_NEED_CLEANUP unconditionally") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/e1306007458b8891c88c4f20c966a17595f766b0.174264379... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/net.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/io_uring/net.c +++ b/io_uring/net.c @@ -1427,6 +1427,7 @@ int io_send_zc(struct io_kiocb *req, uns */ if (!(issue_flags & IO_URING_F_UNLOCKED)) { io_notif_flush(zc->notif); + zc->notif = NULL; io_req_msg_cleanup(req, 0); } io_req_set_res(req, ret, IORING_CQE_F_MORE); @@ -1487,6 +1488,7 @@ int io_sendmsg_zc(struct io_kiocb *req, */ if (!(issue_flags & IO_URING_F_UNLOCKED)) { io_notif_flush(sr->notif); + sr->notif = NULL; io_req_msg_cleanup(req, 0); } io_req_set_res(req, ret, IORING_CQE_F_MORE);