linux-kernel - [PATCH 3/5] leaking_addresses: add range check for vsyscall memory

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Message-Id: <1512621145-4783-4-git-send-email-me@tobin.cc>
Date:   Thu,  7 Dec 2017 15:32:23 +1100
From:   "Tobin C. Harding" <me@...in.cc>
To:     me@...in.cc, kaiwan.billimoria@...il.com
Cc:     "Kirill A. Shutemov" <kirill@...temov.name>,
        Alexander Kapshuk <alexander.kapshuk@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-hardening@...ts.openwall.com
Subject: [PATCH 3/5] leaking_addresses: add range check for vsyscall memory

Currently script checks only first and last address in the vsyscall
memory range. We can do better than this.

When checking for false positives against $match, convert $match to
a hexadecimal value then check if it lies within the range of vsyscall
addresses.

Signed-off-by: Tobin C. Harding <me@...in.cc>
---
 scripts/leaking_addresses.pl | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index 066c609b1adb..cb69ccd4153a 100755
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -20,6 +20,7 @@ use Cwd 'abs_path';
 use Term::ANSIColor qw(:constants);
 use Getopt::Long qw(:config no_auto_abbrev);
 use Config;
+use bigint qw/hex/;
 
 my $P = $0;
 my $V = '0.01';
@@ -196,17 +197,24 @@ sub is_false_positive
 		return 1;
 	}
 
-	if (is_x86_64()) {
-		# vsyscall memory region, we should probably check against a range here.
-		if ($match =~ '\bf{10}600000\b' or
-		    $match =~ '\bf{10}601000\b') {
-			return 1;
-		}
+	if (is_x86_64() and is_in_vsyscall_memory_region($match)) {
+		return 1;
 	}
 
 	return 0;
 }
 
+sub is_in_vsyscall_memory_region
+{
+	my ($match) = @_;
+
+	my $hex = hex($match);
+	my $region_min = hex("0xffffffffff600000");
+	my $region_max = hex("0xffffffffff601000");
+
+	return ($hex >= $region_min and $hex <= $region_max);
+}
+
 # True if argument potentially contains a kernel address.
 sub may_leak_address
 {
-- 
2.7.4