[PATCH 5.10 002/306] io_uring: limit fixed table size by RLIMIT_NOFILE

[Greg Kroah-Hartman]

From: Pavel Begunkov <asml.silence@xxxxxxxxx>

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@xxxxxxxxxxxxxxx
Suggested-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/b2756c340aed7d6c0b302c26dab50c6c5907f4ce.1629451684.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/io_uring.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7579,6 +7579,8 @@ static int io_sqe_files_register(struct
 		return -EINVAL;
 	if (nr_args > IORING_MAX_FIXED_FILES)
 		return -EMFILE;
+	if (nr_args > rlimit(RLIMIT_NOFILE))
+		return -EMFILE;
 
 	file_data = kzalloc(sizeof(*ctx->file_data), GFP_KERNEL);
 	if (!file_data)