From 0b523769ebb9473c60df1b0f70615aa82ebac2c9 Mon Sep 17 00:00:00 2001 From: Joe Perches Date: Mon, 8 May 2017 15:55:36 -0700 Subject: [PATCH] checkpatch: add ability to find bad uses of vsprintf %p extensions %pK was at least once misused at %pk in an out-of-tree module. This lead to some security concerns. Add the ability to track single and multiple line statements for misuses of %p. [akpm@linux-foundation.org: add helpful comment into lib/vsprintf.c] [akpm@linux-foundation.org: text tweak] Link: http://lkml.kernel.org/r/163a690510e636a23187c0dc9caa09ddac6d4cde.1488228427.git.joe@perches.com Signed-off-by: Joe Perches Acked-by: Kees Cook Acked-by: William Roberts Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 3 +++ scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 176641c..2d41de3 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1477,6 +1477,9 @@ int kptr_restrict __read_mostly; * by an extra set of alphanumeric characters that are extended format * specifiers. * + * Please update scripts/checkpatch.pl when adding/removing conversion + * characters. (Search for "check for vsprintf extension"). + * * Right now we handle: * * - 'F' For symbolic function descriptor pointers with offset diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 30eeba4..732bb3e 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -5663,6 +5663,32 @@ sub process { } } + # check for vsprintf extension %p misuses + if ($^V && $^V ge 5.10.0 && + defined $stat && + $stat =~ /^\+(?![^\{]*\{\s*).*\b(\w+)\s*\(.*$String\s*,/s && + $1 !~ /^_*volatile_*$/) { + my $bad_extension = ""; + 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(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) { + $bad_extension = $1; + last; + } + } + if ($bad_extension ne "") { + my $stat_real = raw_line($linenr, 0); + for (my $count = $linenr + 1; $count <= $lc; $count++) { + $stat_real = $stat_real . "\n" . raw_line($count, 0); + } + WARN("VSPRINTF_POINTER_EXTENSION", + "Invalid vsprintf pointer extension '$bad_extension'\n" . "$here\n$stat_real\n"); + } + } + # Check for misused memsets if ($^V && $^V ge 5.10.0 && defined $stat && -- 2.7.4