io_uring: limit fixed table size by RLIMIT_NOFILE

commit 3a1b8a4e843f96b636431450d8d79061605cf74b upstream.

Limit the number of files in io_uring fixed tables by RLIMIT_NOFILE,
that's the first and the simpliest restriction that we should impose.

Cc: stable@vger.kernel.org
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b2756c340aed7d6c0b302c26dab50c6c5907f4ce.1629451684.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a2e20a6fbfed8e85c05be4e22fff8201b6c5ac46..0d6f1b335fb376274b480d550d302bd69cea04b6 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7722,6 +7722,8 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
                return -EINVAL;
        if (nr_args > IORING_MAX_FIXED_FILES)
                return -EMFILE;
+       if (nr_args > rlimit(RLIMIT_NOFILE))
+               return -EMFILE;
        ret = io_rsrc_node_switch_start(ctx);
        if (ret)
                return ret;