io_uring: io_wq_submit_work() should not touch req->rw (fd6c2e4c) · Commits · 戴 / test

I've been chasing a weird and obscure crash that was userspace stack corruption, and finally narrowed it down to a bit flip that made a stack address invalid. io_wq_submit_work() unconditionally flips the req->rw.ki_flags IOCB_NOWAIT bit, but since it's a generic work handler, this isn't valid. Normal read/write operations own that part of the request, on other types it could be something else. Move the IOCB_NOWAIT clear to the read/write handlers where it belongs. Signed-off-by:

Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -1817,6 +1817,10 @@ static int io_read(struct io_kiocb req, struct io_kiocb *nxt,
		return ret;
		}

		/* Ensure we clear previously set non-block flag */
		if (!force_nonblock)
		req->rw.ki_flags &= ~IOCB_NOWAIT;

		file = req->file;
		io_size = ret;
		if (req->flags & REQ_F_LINK)
		@@ -1906,6 +1910,10 @@ static int io_write(struct io_kiocb req, struct io_kiocb *nxt,
		return ret;
		}

		/* Ensure we clear previously set non-block flag */
		if (!force_nonblock)
		req->rw.ki_flags &= ~IOCB_NOWAIT;

		file = kiocb->ki_filp;
		io_size = ret;
		if (req->flags & REQ_F_LINK)
		@@ -3274,9 +3282,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
		struct io_kiocb *nxt = NULL;
		int ret = 0;

		/* Ensure we clear previously set non-block flag */
		req->rw.ki_flags &= ~IOCB_NOWAIT;

		if (work->flags & IO_WQ_WORK_CANCEL)
		ret = -ECANCELED;

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