From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752015AbeB0CY7 (ORCPT ); Mon, 26 Feb 2018 21:24:59 -0500 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:46221 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751991AbeB0CYz (ORCPT ); Mon, 26 Feb 2018 21:24:55 -0500 X-ME-Sender: From: "Tobin C. Harding" To: Andrew Morton Cc: "Tobin C. Harding" , Joe Perches , Andy Whitcroft , linux-kernel@vger.kernel.org Subject: [PATCH v3 4/4] checkpatch: warn for use of %px Date: Tue, 27 Feb 2018 13:24:23 +1100 Message-Id: <1519698263-17783-5-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1519698263-17783-1-git-send-email-me@tobin.cc> References: <1519698263-17783-1-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 | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 679a10298cb5..cf1a1070fc4a 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -5797,16 +5797,33 @@ 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(?![\WSsBKRraEhMmIiUDdgVCbGNOx]).)/) { - $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, $lc); @@ -5819,7 +5836,7 @@ sub process { } WARN("VSPRINTF_POINTER_EXTENSION", - "$ext_type vsprintf pointer extension '$bad_extension'$use\n" . "$here\n$stat_real\n"); + "Invalid vsprintf pointer extension '$bad_specifier'\n" . "$here\n$stat_real\n"); } } -- 2.7.4