[PATCH 3/4] io_uring: fix ovelapped memcpy in io_req_map_rw()

Pavel Begunkov
2020-09-05T21:48:30Z

When io_req_map_rw() is called from io_rw_prep_async(), it memcpy()
iorw->iter into itself. Even though it doesn't lead to an error, such a
memcpy()'s aliasing rules violation is considered to be a bad practise.

Inline io_req_map_rw() into io_rw_prep_async(). We don't really need any
remapping there, so it's much simpler than the generic implementation.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 03808e865dde..fc2aaaaca908 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2986,7 +2986,10 @@ static inline int io_rw_prep_async(struct io_kiocb *req, int rw,
if (unlikely(ret < 0))
return ret;

- io_req_map_rw(req, iov, iorw->fast_iov, &iorw->iter);
+ iorw->bytes_done = 0;
+ iorw->free_iovec = iov;
+ if (iov)
+ req->flags |= REQ_F_NEED_CLEANUP;
return 0;
}

--
2.24.0