From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98914C433EF for ; Thu, 30 Jun 2022 14:10:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236789AbiF3OKy (ORCPT ); Thu, 30 Jun 2022 10:10:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236759AbiF3OKX (ORCPT ); Thu, 30 Jun 2022 10:10:23 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9CEC779728; Thu, 30 Jun 2022 06:55:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 77610B82AEE; Thu, 30 Jun 2022 13:55:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA3DFC34115; Thu, 30 Jun 2022 13:55:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656597320; bh=bC4dbYqaiI9cHdVVOeiAurkri0bMBe9DGGDutSfc0fQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YTso+POVxVG00B+RyKmxOHw/7qEXk/wjXuUI03XAFY8n9F3Tfuqxz+dAcZmoVzJox tYwbuC7uTPwub1CbDxt8fOfGBeKGtMe/i88/JNwvoxsvvvfpQpNg3CXwv183+CIWrA Vtc52cV0q7MIgwgC7djFIkqbejEIT8jEk0sLabIE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Begunkov Subject: [PATCH 5.15 28/28] io_uring: fix not locked access to fixed buf table Date: Thu, 30 Jun 2022 15:47:24 +0200 Message-Id: <20220630133233.758061530@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220630133232.926711493@linuxfoundation.org> References: <20220630133232.926711493@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Begunkov commit 05b538c1765f8d14a71ccf5f85258dcbeaf189f7 upstream. We can look inside the fixed buffer table only while holding ->uring_lock, however in some cases we don't do the right async prep for IORING_OP_{WRITE,READ}_FIXED ending up with NULL req->imu forcing making an io-wq worker to try to resolve the fixed buffer without proper locking. Move req->imu setup into early req init paths, i.e. io_prep_rw(), which is called unconditionally for rw requests and under uring_lock. Fixes: 634d00df5e1cf ("io_uring: add full-fledged dynamic buffers support") Signed-off-by: Pavel Begunkov Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2932,15 +2932,24 @@ static int io_prep_rw(struct io_kiocb *r kiocb->ki_complete = io_complete_rw; } + /* used for fixed read/write too - just read unconditionally */ + req->buf_index = READ_ONCE(sqe->buf_index); + req->imu = NULL; + if (req->opcode == IORING_OP_READ_FIXED || req->opcode == IORING_OP_WRITE_FIXED) { - req->imu = NULL; + struct io_ring_ctx *ctx = req->ctx; + u16 index; + + if (unlikely(req->buf_index >= ctx->nr_user_bufs)) + return -EFAULT; + index = array_index_nospec(req->buf_index, ctx->nr_user_bufs); + req->imu = ctx->user_bufs[index]; io_req_set_rsrc_node(req); } req->rw.addr = READ_ONCE(sqe->addr); req->rw.len = READ_ONCE(sqe->len); - req->buf_index = READ_ONCE(sqe->buf_index); return 0; } @@ -3066,18 +3075,9 @@ static int __io_import_fixed(struct io_k static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter) { - struct io_ring_ctx *ctx = req->ctx; - struct io_mapped_ubuf *imu = req->imu; - u16 index, buf_index = req->buf_index; - - if (likely(!imu)) { - if (unlikely(buf_index >= ctx->nr_user_bufs)) - return -EFAULT; - index = array_index_nospec(buf_index, ctx->nr_user_bufs); - imu = READ_ONCE(ctx->user_bufs[index]); - req->imu = imu; - } - return __io_import_fixed(req, rw, iter, imu); + if (WARN_ON_ONCE(!req->imu)) + return -EFAULT; + return __io_import_fixed(req, rw, iter, req->imu); } static void io_ring_submit_unlock(struct io_ring_ctx *ctx, bool needs_lock)