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 X-Spam-Level: X-Spam-Status: No, score=-10.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F287C3279B for ; Fri, 6 Jul 2018 20:48:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0256322BD3 for ; Fri, 6 Jul 2018 20:48:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ttrt2y8C" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0256322BD3 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934448AbeGFUsM (ORCPT ); Fri, 6 Jul 2018 16:48:12 -0400 Received: from mail-yb0-f201.google.com ([209.85.213.201]:41032 "EHLO mail-yb0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933833AbeGFUsK (ORCPT ); Fri, 6 Jul 2018 16:48:10 -0400 Received: by mail-yb0-f201.google.com with SMTP id s46-v6so11228743ybe.8 for ; Fri, 06 Jul 2018 13:48:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:date:message-id:subject:from:to:cc; bh=UdIVhqKshfapI0b3L3MMkWLnlZm4PWM7dqfeHLlrp7Q=; b=ttrt2y8CfvzN5D2C1R3DxZv7gGFEfrVnWx9Om/2KT/xhsRMcaJ5Zp90HAWchOBA2jT 3jPv+OcLywx6ydHPDKKpxrbAT+nNMkabizddGcOIk0mgqoW7CGi6uY5e8hyjnBkZtCAi V14JdP/4jPKLqvZmBpOxCzR5ADs9EIwJ8CynPGoVMkySLX1eMF4HKMEem2QwUWhWvJUt 8qOtDC76OoyB9FbKji3ARnx/RgAX0KxxyaqzTQR1VNB+lXeqnb+GcCsJGyprOfocnnAg LLzHcgS0ucdKi9uN8stisiktb5IRwOLRL0fBt5tDr9fc80PhXvEOjNMakW4HF1oAFLhh Hj8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to:cc; bh=UdIVhqKshfapI0b3L3MMkWLnlZm4PWM7dqfeHLlrp7Q=; b=hcVJnpiTsdcgBhAAKKUo0m/3778BC7IJK0oY7UD36Z4D9mxv1RJuPH90PHt8bXtUBq s48OCOaWm2rw4eXIhjiemMy6jEmyGBMCqKJ6qDE/D4HETGIL5p5cW/BCSlhidy2eSDr1 L8AbDAwfZXUf8X9BNWKhzENTMtOKmXXXa90Kh/tbWQgAVXreunLz2xEbo2X4F8Rg/FWU sXp83mxJ/mwKA3NCAq/s5Z2bF4b/WcTYlzeVRbY9LS3qdS0ZfwemXQMWrkfL61CIi5Na QQ1LMKjQFIEMgaXRYEzqExT5n6CI5gORYkNsLiTa3SrBgYySFk7lQvxWQQ3vLJILZcww Yyvw== X-Gm-Message-State: APt69E1DtZkTSKDLlqkWmWYN2asUgw5rgZ2jlw3CDJhT50cdgSActXVh kYNy4C0KPfONZpMakzUE0QTzgkm0oA== X-Google-Smtp-Source: AAOMgpeKhrQV6gqo9QZPAHfsWUuh4Jiz7h5VHtjy9/VIh9CJSEej+1pCVcCfW9MjQifLHCqoAbODVJSAWw== MIME-Version: 1.0 X-Received: by 2002:a0d:c901:: with SMTP id l1-v6mr3738708ywd.35.1530910090085; Fri, 06 Jul 2018 13:48:10 -0700 (PDT) Date: Fri, 6 Jul 2018 22:48:03 +0200 Message-Id: <20180706204803.131152-1-jannh@google.com> X-Mailer: git-send-email 2.18.0.203.gfac676dfb9-goog Subject: [PATCH v2] IB/mlx5: fix uaccess beyond "count" in debugfs read/write handlers From: Jann Horn To: Leon Romanovsky , Doug Ledford , Jason Gunthorpe , jannh@google.com Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In general, accessing userspace memory beyond the length of the supplied buffer in VFS read/write handlers can lead to both kernel memory corruption (via kernel_read()/kernel_write(), which can e.g. be triggered via sys_splice()) and privilege escalation inside userspace. In this case, the affected files are in debugfs (and should therefore only be accessible to root), and the read handlers check that *pos is zero (meaning that at least sys_splice() can't trigger kernel memory corruption). Because of the root requirement, this is not a security fix, but rather a cleanup. For the read handlers, fix it by using simple_read_from_buffer() instead of custom logic. Add min() calls to the write handlers. changed in v2: - also fix write handlers Fixes: 4a2da0b8c078 ("IB/mlx5: Add debug control parameters for congestion control") Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters") Signed-off-by: Jann Horn --- drivers/infiniband/hw/mlx5/cong.c | 9 +-------- drivers/infiniband/hw/mlx5/mr.c | 32 ++++++++----------------------- 2 files changed, 9 insertions(+), 32 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/cong.c b/drivers/infiniband/hw/mlx5/cong.c index 985fa2637390..7e4e358a4fd8 100644 --- a/drivers/infiniband/hw/mlx5/cong.c +++ b/drivers/infiniband/hw/mlx5/cong.c @@ -359,9 +359,6 @@ static ssize_t get_param(struct file *filp, char __user *buf, size_t count, int ret; char lbuf[11]; - if (*pos) - return 0; - ret = mlx5_ib_get_cc_params(param->dev, param->port_num, offset, &var); if (ret) return ret; @@ -370,11 +367,7 @@ static ssize_t get_param(struct file *filp, char __user *buf, size_t count, if (ret < 0) return ret; - if (copy_to_user(buf, lbuf, ret)) - return -EFAULT; - - *pos += ret; - return ret; + return simple_read_from_buffer(buf, count, pos, lbuf, ret); } static const struct file_operations dbg_cc_fops = { diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index 90a9c461cedc..308456d28afb 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -271,16 +271,16 @@ static ssize_t size_write(struct file *filp, const char __user *buf, { struct mlx5_cache_ent *ent = filp->private_data; struct mlx5_ib_dev *dev = ent->dev; - char lbuf[20]; + char lbuf[20] = {0}; u32 var; int err; int c; - if (copy_from_user(lbuf, buf, sizeof(lbuf))) + count = min(count, sizeof(lbuf) - 1); + if (copy_from_user(lbuf, buf, count)) return -EFAULT; c = order2idx(dev, ent->order); - lbuf[sizeof(lbuf) - 1] = 0; if (sscanf(lbuf, "%u", &var) != 1) return -EINVAL; @@ -310,19 +310,11 @@ static ssize_t size_read(struct file *filp, char __user *buf, size_t count, char lbuf[20]; int err; - if (*pos) - return 0; - err = snprintf(lbuf, sizeof(lbuf), "%d\n", ent->size); if (err < 0) return err; - if (copy_to_user(buf, lbuf, err)) - return -EFAULT; - - *pos += err; - - return err; + return simple_read_from_buffer(buf, count, pos, lbuf, err); } static const struct file_operations size_fops = { @@ -337,16 +329,16 @@ static ssize_t limit_write(struct file *filp, const char __user *buf, { struct mlx5_cache_ent *ent = filp->private_data; struct mlx5_ib_dev *dev = ent->dev; - char lbuf[20]; + char lbuf[20] = {0}; u32 var; int err; int c; - if (copy_from_user(lbuf, buf, sizeof(lbuf))) + count = min(count, sizeof(lbuf) - 1); + if (copy_from_user(lbuf, buf, count)) return -EFAULT; c = order2idx(dev, ent->order); - lbuf[sizeof(lbuf) - 1] = 0; if (sscanf(lbuf, "%u", &var) != 1) return -EINVAL; @@ -372,19 +364,11 @@ static ssize_t limit_read(struct file *filp, char __user *buf, size_t count, char lbuf[20]; int err; - if (*pos) - return 0; - err = snprintf(lbuf, sizeof(lbuf), "%d\n", ent->limit); if (err < 0) return err; - if (copy_to_user(buf, lbuf, err)) - return -EFAULT; - - *pos += err; - - return err; + return simple_read_from_buffer(buf, count, pos, lbuf, err); } static const struct file_operations limit_fops = { -- 2.18.0.203.gfac676dfb9-goog