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@xxxxxxxxx> --- This one was fun to find, random flip of a bit in an unrelated struct... diff --git a/fs/io_uring.c b/fs/io_uring.c index b7800def3090..b632bd9222d9 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -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) @@ -3272,9 +3280,6 @@ 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; -- Jens Axboe
