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.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 2009d1cda606c0e3d1591e60d37b170beca313bd..0db463599b00fcb0c2d385067566169426211b96 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7579,6 +7579,8 @@ 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;
 
        file_data = kzalloc(sizeof(*ctx->file_data), GFP_KERNEL);
        if (!file_data)