From: Xiaoguang Wang xiaoguang.wang@linux.alibaba.com
mainline inclusion from mainline-5.7-rc1 commit 45097daea2f4e89bdb1c98359f78d0d6feb8e5c8 category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA ---------------------------
In io_read_prep() or io_write_prep(), io_req_map_rw() takes struct io_async_rw's fast_iov as argument to call io_import_iovec(), and if io_import_iovec() uses struct io_async_rw's fast_iov as valid iovec array, later indeed io_req_map_rw() does not need to do the memcpy operation, because they are same pointers.
Signed-off-by: Xiaoguang Wang xiaoguang.wang@linux.alibaba.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- fs/io_uring.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 80dc4b0dd1f0..2f0f65eb59a4 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2487,8 +2487,9 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size, req->io->rw.iov = iovec; if (!req->io->rw.iov) { req->io->rw.iov = req->io->rw.fast_iov; - memcpy(req->io->rw.iov, fast_iov, - sizeof(struct iovec) * iter->nr_segs); + if (req->io->rw.iov != fast_iov) + memcpy(req->io->rw.iov, fast_iov, + sizeof(struct iovec) * iter->nr_segs); } else { req->flags |= REQ_F_NEED_CLEANUP; }