The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3a1b8a4e843f96b636431450d8d79061605cf74b 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

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.162945168... Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/fs/io_uring.c b/fs/io_uring.c index 706ac8c03b95..9a021fe6c461 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7733,6 +7733,8 @@ 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;