From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754719AbdLFDh7 (ORCPT ); Tue, 5 Dec 2017 22:37:59 -0500 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:60713 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754675AbdLFDhc (ORCPT ); Tue, 5 Dec 2017 22:37:32 -0500 X-ME-Sender: From: "Tobin C. Harding" To: Joe Perches Cc: "Tobin C. Harding" , Andy Whitcroft , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] checkpatch: warn for use of %px Date: Wed, 6 Dec 2017 14:37:08 +1100 Message-Id: <1512531428-3592-4-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1512531428-3592-1-git-send-email-me@tobin.cc> References: <1512531428-3592-1-git-send-email-me@tobin.cc> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Usage of the new %px specifier potentially leaks sensitive inforamtion. Printing kernel addresses exposes the kernel layout in memory, this is potentially exploitable. We have tools in the kernel to help us do the right thing. We can have checkpatch warn developers of potential dangers of using %px. Have checkpatch emit a warning for usage of specifier %px. Signed-off-by: Tobin C. Harding Co-developed-by: Joe Perches Acked-by: Joe Perches --- scripts/checkpatch.pl | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 4534c9a9aefa..6df99d1ebca5 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -5750,21 +5750,38 @@ sub process { defined $stat && $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s && $1 !~ /^_*volatile_*$/) { - my $bad_extension = ""; + my $specifier; + my $extension; + my $bad_specifier = ""; + my $stat_real; + my $lc = $stat =~ tr@\n@@; $lc = $lc + $linenr; for (my $count = $linenr; $count <= $lc; $count++) { my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0)); $fmt =~ s/%%//g; - if ($fmt =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGNOx]).)/) { - $bad_extension = $1; - last; + + while ($fmt =~ /(\%[\*\d\.]*p(\w))/g) { + $specifier = $1; + $extension = $2; + if ($extension !~ /[FfSsBKRraEhMmIiUDdgVCbGNOx]/) { + $bad_specifier = $specifier; + last; + } + if ($extension eq "x" && !defined($stat_real)) { + if (!defined($stat_real)) { + $stat_real = get_stat_real($linenr, $lc); + } + WARN("VSPRINTF_SPECIFIER_PX", + "Using vsprintf specifier '\%px' potentially exposes the kernel memory layout, if you don't really need the address please consider using '\%p'.\n" . "$here\n$stat_real\n"); + } } + } - if ($bad_extension ne "") { - my $stat_real = get_stat_real($linenr, $lc); + if ($bad_specifier ne "") { + $stat_real = get_stat_real($linenr, $lc); WARN("VSPRINTF_POINTER_EXTENSION", - "Invalid vsprintf pointer extension '$bad_extension'\n" . "$here\n$stat_real\n"); + "Invalid vsprintf pointer extension '$bad_specifier'\n" . "$here\n$stat_real\n"); } } -- 2.7.4