io_uring/rw: free potentially allocated iovec on cache put failure

If a read/write request goes through io_req_rw_cleanup() and has an
allocated iovec attached and fails to put to the rw_cache, then it may
end up with an unaccounted iovec pointer. Have io_rw_recycle() return
whether it recycled the request or not, and use that to gauge whether to
free a potential iovec or not.

Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: axboe

io_uring/rw.c

@@ -144,19 +144,22 @@ static inline int io_import_rw_buffer(int rw, struct io_kiocb *req,
 	return 0;
 }
 
-static void io_rw_recycle(struct io_kiocb *req, unsigned int issue_flags)
+static bool io_rw_recycle(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_async_rw *rw = req->async_data;
 
 	if (unlikely(issue_flags & IO_URING_F_UNLOCKED))
-		return;
+		return false;
 
 	io_alloc_cache_vec_kasan(&rw->vec);
 	if (rw->vec.nr > IO_VEC_CACHE_SOFT_CAP)
 		io_vec_free(&rw->vec);
 
-	if (io_alloc_cache_put(&req->ctx->rw_cache, rw))
+	if (io_alloc_cache_put(&req->ctx->rw_cache, rw)) {
 		io_req_async_data_clear(req, 0);
+		return true;
+	}
+	return false;
 }
 
 static void io_req_rw_cleanup(struct io_kiocb *req, unsigned int issue_flags)
@@ -190,7 +193,11 @@ static void io_req_rw_cleanup(struct io_kiocb *req, unsigned int issue_flags)
 	 */
 	if (!(req->flags & (REQ_F_REISSUE | REQ_F_REFCOUNT))) {
 		req->flags &= ~REQ_F_NEED_CLEANUP;
-		io_rw_recycle(req, issue_flags);
+		if (!io_rw_recycle(req, issue_flags)) {
+			struct io_async_rw *rw = req->async_data;
+
+			io_vec_free(&rw->vec);
+		}
 	}
 }