From 917342c3714358991d8ac2bd29bff8f6ea62f077 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Fri, 20 Aug 2021 10:36:35 +0100
Subject: [PATCH] io_uring: limit fixed table size by RLIMIT_NOFILE
Git-commit: 3a1b8a4e843f96b636431450d8d79061605cf74b
Patch-mainline: v5.15-rc1
References: stable-5.14.4

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 fs/io_uring.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a2e20a6fbfed..0d6f1b335fb3 100644
--- 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;
-- 
2.26.2