io_uring/sync: validate passed in offset

[ Upstream commit 649dd18 ]

Check if the passed in offset is negative once cast to sync->off. This
ensures that -EINVAL is returned for that case, like it would be for
sync_file_range(2).

Fixes: c992fe2 ("io_uring: add fsync support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: axboe

io_uring/sync.c

@@ -61,6 +61,8 @@ int io_fsync_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return -EINVAL;
 
 	sync->off = READ_ONCE(sqe->off);
+	if (sync->off < 0)
+		return -EINVAL;
 	sync->len = READ_ONCE(sqe->len);
 	return 0;
 }