From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtiye29EEjmXZ+kLcJnR+wgOvP36ENkx/lwZzZLm+B0OR6+W9X2rNJKuSYjRVxpDHWAjw5a ARC-Seal: i=1; a=rsa-sha256; t=1520824076; cv=none; d=google.com; s=arc-20160816; b=YOg5EEtQzSgVDwKBI9MkUh6q+5shpjevJUCb7mWjZBbe8trSRoVTw639s6ALWxlgAk y52YXVQCzv+6DEtdMFMY5yXcEsiU9BMGzeimNp6z5sAu0/gWVVcTyicADAOTGc9IQNMc K5rNOcGHWKXLi+BeRYvIFDqsFiuRtsUdr6Yk5quQ58KCaS56GSwCyXrIjJ4URBEHiCnB 1WeYYSuD3FtZZo315C9lpXLgm8R9sBqeRoKLrn7s8JCafdhkPuw/ocB4iMAPwBg+Zf8M NyMsNLSyNudRV1WISPkedwsNlFoafbx4UwywyRPBVqQ9k6+OMxsw2sCpBLdclpH/k2mF 1eUg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=in-reply-to:subject:message-id:date:cc:to:from:mime-version :content-transfer-encoding:content-disposition :arc-authentication-results; bh=34NVLQOtYvIvmxbxEgTLuAse/WMak+4BTmQFXoDNWIw=; b=kL/P7oPddsE6dYu58UZ9ghw6rPPgReXfybGIgwY1mu2GS8g8zWfWIe7gAvZXAovXHA hqveDFTJmOYpZUSaA4tuVzl+TGqSSkJ2BReeubtWnDmD73akidkKyPdLLLevTWrc5+Ug gLXpy3tXA5hCIbnCaz5KMIrxen/lDh2ya7e5zE1pycgebpLZis2fUEyujyF9Ii7wpgBi ACzE53Sg/H11DtVojxgMObzW3bgEA8DYypUxc24l7rfzwBwgrGl7sIxLFEoMwG3zt2d+ ihuO+mgZmqa7TT/9fTKRK2ci4N6kDBB3bFaKxN6LTQGcal2jgKxjiGLChlD8L9t1ezNe q3dQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of ben@decadent.org.uk designates 88.96.1.126 as permitted sender) smtp.mailfrom=ben@decadent.org.uk Authentication-Results: mx.google.com; spf=pass (google.com: domain of ben@decadent.org.uk designates 88.96.1.126 as permitted sender) smtp.mailfrom=ben@decadent.org.uk Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, torvalds@linux-foundation.org, "Al Viro" , kernel-hardening@lists.openwall.com, gregkh@linuxfoundation.org, linux-arch@vger.kernel.org, alan@linux.intel.com, "Thomas Gleixner" , "Dan Williams" Date: Mon, 12 Mar 2018 03:06:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 57/76] vfs, fdtable: Prevent bounds-check bypass via speculative execution In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594699621976171926?= X-GMAIL-MSGID: =?utf-8?q?1594699626255780781?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.16.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit 56c30ba7b348b90484969054d561f711ba196507 upstream. 'fd' is a user controlled value that is used as a data dependency to read from the 'fdt->fd' array. In order to avoid potential leaks of kernel memory values, block speculative execution of the instruction stream that could issue reads based on an invalid 'file *' returned from __fcheck_files. Co-developed-by: Elena Reshetova Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ben Hutchings --- include/linux/fdtable.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -76,8 +77,10 @@ static inline struct file *__fcheck_file { struct fdtable *fdt = rcu_dereference_raw(files->fdt); - if (fd < fdt->max_fds) + if (fd < fdt->max_fds) { + fd = array_index_nospec(fd, fdt->max_fds); return rcu_dereference_raw(fdt->fd[fd]); + } return NULL; }