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authorPavel Begunkov <asml.silence@gmail.com>2023-01-12 16:08:56 +0300
committerJens Axboe <axboe@kernel.dk>2023-01-13 17:32:46 +0300
commit544d163d659d45a206d8929370d5a2984e546cb7 (patch)
treefc783da4c9a3d8b8c0badd9ac551ea6cef2b5bd7 /io_uring
parent6e5aedb9324aab1c14a23fae3d8eeb64a679c20e (diff)
downloadlinux-544d163d659d45a206d8929370d5a2984e546cb7.tar.xz
io_uring: lock overflowing for IOPOLL
syzbot reports an issue with overflow filling for IOPOLL: WARNING: CPU: 0 PID: 28 at io_uring/io_uring.c:734 io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734 CPU: 0 PID: 28 Comm: kworker/u4:1 Not tainted 6.2.0-rc3-syzkaller-16369-g358a161a6a9e #0 Workqueue: events_unbound io_ring_exit_work Call trace:  io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734  io_req_cqe_overflow+0x5c/0x70 io_uring/io_uring.c:773  io_fill_cqe_req io_uring/io_uring.h:168 [inline]  io_do_iopoll+0x474/0x62c io_uring/rw.c:1065  io_iopoll_try_reap_events+0x6c/0x108 io_uring/io_uring.c:1513  io_uring_try_cancel_requests+0x13c/0x258 io_uring/io_uring.c:3056  io_ring_exit_work+0xec/0x390 io_uring/io_uring.c:2869  process_one_work+0x2d8/0x504 kernel/workqueue.c:2289  worker_thread+0x340/0x610 kernel/workqueue.c:2436  kthread+0x12c/0x158 kernel/kthread.c:376  ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:863 There is no real problem for normal IOPOLL as flush is also called with uring_lock taken, but it's getting more complicated for IOPOLL|SQPOLL, for which __io_cqring_overflow_flush() happens from the CQ waiting path. Reported-and-tested-by: syzbot+6805087452d72929404e@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
-rw-r--r--io_uring/rw.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 8227af2e1c0f..9c3ddd46a1ad 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -1062,7 +1062,11 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
continue;
req->cqe.flags = io_put_kbuf(req, 0);
- io_fill_cqe_req(req->ctx, req);
+ if (unlikely(!__io_fill_cqe_req(ctx, req))) {
+ spin_lock(&ctx->completion_lock);
+ io_req_cqe_overflow(req);
+ spin_unlock(&ctx->completion_lock);
+ }
}
if (unlikely(!nr_events))