From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsAcjRGx6EBrrEerX2ph18arTE5DO3U9xCRJc1z0TXhFCm5FDg1mRnGu/ymWnvaMzUyrHU1 ARC-Seal: i=1; a=rsa-sha256; t=1520824071; cv=none; d=google.com; s=arc-20160816; b=0ql5XsNXyxpOLAJnXzRmlar5C4Jn9M1Urn4J1XNZBPPUWDpb+ici8BsoayMJbuEjco ril9r40jurT4qu2wu3JW7+dcBPk1dcdeajQuzl3w0HyCkDbKWLiVikZlvjZ2jSdX9qgo fFEKazaZzC2O27kxONavZ1QuL6yn2Im2/+Owenn0ELpfC8xgy+r7JpkyjPdmF5J10ttF xiBr+K07s3a2eiGRKZw619ayXhGFTqD9VpfcZUKUzpeanScjaEd2GpIw6hVmdW+UaJ02 TJK94YFPIB9Uu8p3rbMKyj+jZUKj3hpKqcTFULI/ddtuY4wwhXyiw2YZJL2x/wDKhFBC JoZg== 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=g/aj8qO5aFf00yIgCukCNBgX6uzLTUHhZnDfgXfrwlg=; b=doOAfKgTFL2jC+5PzAdpKOoal/q1Y9J7kaHYsfgPF5ARPedivdE2COQMYOD8PFJ6jM NnJC8qmqaH91ezONuXfDj9m65qGArqYl7m0KQbOHuhZAVDIIyDA85smOmh5TufIieXFD PQOnNFx2AhwexT0wgIB875SGgHIXC22V2Cd0DI7Wtcu7SUy6ug71A6kYobWWNkTCO7vz xW9E9DOY1htlNrcljcjMW3dNdejJhHLWgBh5CfEFnxragL0BMbpBgT29iZnG5pPa8fK/ akGvmOd+xZjpxOBmLTtb+vSoQEC4haKLllWg//O6kJKmD7fFvU50tniA9FGv81sn5LiK g4Iw== 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, linux-arch@vger.kernel.org, "Al Viro" , gregkh@linuxfoundation.org, "Thomas Gleixner" , "Dan Williams" , torvalds@linux-foundation.org, kernel-hardening@lists.openwall.com, alan@linux.intel.com Date: Mon, 12 Mar 2018 03:03:34 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 088/104] 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?1594699621976171926?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.2.101-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 [bwh: Backported to 3.2: adjust context] 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 @@ -85,8 +86,10 @@ static inline struct file * fcheck_files struct file * file = NULL; struct fdtable *fdt = files_fdtable(files); - if (fd < fdt->max_fds) + if (fd < fdt->max_fds) { + fd = array_index_nospec(fd, fdt->max_fds); file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); + } return file; }