From fd6c2e4c063d64511657ad0031a1677b6a914859 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 18 Dec 2019 12:19:41 -0700 Subject: [PATCH] io_uring: io_wq_submit_work() should not touch req->rw 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 --- fs/io_uring.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 81e7fe6dee18..6f084e3cf835 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) @@ -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;