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 97C7FC3279B for ; Fri, 6 Jul 2018 15:25:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E15F2241F for ; Fri, 6 Jul 2018 15:25:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="d4Mi1Doi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E15F2241F 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 S932905AbeGFPY4 (ORCPT ); Fri, 6 Jul 2018 11:24:56 -0400 Received: from mail-ua0-f201.google.com ([209.85.217.201]:55998 "EHLO mail-ua0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932590AbeGFPYy (ORCPT ); Fri, 6 Jul 2018 11:24:54 -0400 Received: by mail-ua0-f201.google.com with SMTP id r19-v6so3516200ual.22 for ; Fri, 06 Jul 2018 08:24:54 -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=KUWHNZHeagj/CL6Y8XcnSsfnsgIezm6BP2wsPXYz0LA=; b=d4Mi1DoiI0wnRn2TLfG6L7Z1iaC+ATIk2yqlS9uj6xIGYX3KoMKY4Fx1iwssnE8qUF L3K/AHYDihvy6B5U3dcfwi9s/swgeqRyuPIbBBeC6L86FC6SYaYys2EGc+3ykqCG5EDw v4Abn1w4nEYvmlOGv2wdaeejQSAa6+o+sVu7aAypkVqOvtkk4Z1Nt2yYtWDAtZUHgLPV KWet3YTsDAw5YqhCyGsoMCiIm45uUWEET1lWRbDhAx+XCMpXG99aUQwa25d+T0ddmB7j 6Z9z8l4uwnnAYoJ8/P/VyhwD/UcxPxH/blJMixZFDaPEqNOZbqc8tPwUyPLM9cqY8DXM do5g== 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=KUWHNZHeagj/CL6Y8XcnSsfnsgIezm6BP2wsPXYz0LA=; b=sgwBAN3KmRDqJL11IpgvA9o9Tnks2IqRLVJd2qMXWqUCcOa8+z/EgkTcqFXLcoSuRS 8ZY0kTLzgEm7+03J/qhAUEtOjsDW/vRNfu8LHXPNVyuX4BaxpHN0wnv65zsOq1ireJyM +690XkPOFJegi5+3bJGcCSoo+wg8+4bklUnzh1TTsQcMTtY+1+QIp32FKFn1qTdlba+M RI9hcsoQSGMYVtBoTcIi82NbyZLTr3SP/9tYDHKX1M4pMRuw/LoE9erDJI2EdUK0pLY4 mHDpoXoYt9+xRTbUK3ETQt6pe1RvMmlXuE/AkNEEcM+JCa8Rhgpxhm/tJTWzaz54XByB kQqg== X-Gm-Message-State: APt69E25//9lYN7YjydOjSldp4/lmrfbLJc61t4s7yE6V1Nu0L1aOc5K kbeO9z2RCE0bkzuqQKG+9v1Sbl8FFw== X-Google-Smtp-Source: AAOMgpeR/zSK+wlZSUl/nVjG+EKjlTTLSCWKDhKGdtJedqB6nBMG7goIqdii74RlQg+FsevsiwKCX35CJg== MIME-Version: 1.0 X-Received: by 2002:a1f:3897:: with SMTP id f145-v6mr4618995vka.125.1530890694132; Fri, 06 Jul 2018 08:24:54 -0700 (PDT) Date: Fri, 6 Jul 2018 17:24:49 +0200 Message-Id: <20180706152449.33415-1-jannh@google.com> X-Mailer: git-send-email 2.18.0.399.gad0ab374a1-goog Subject: [PATCH] IB/mlx5: fix uaccess beyond "count" in debugfs read 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 check that *pos is zero (which prevents the sys_splice() trick). Therefore, this is not a security fix, but rather a small cleanup. Fix it by using simple_read_from_buffer() instead of custom logic. 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 | 20 ++------------------ 2 files changed, 3 insertions(+), 26 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..37847add6f74 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -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 = { @@ -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 = { -- 2.18.0.399.gad0ab374a1-goog