From 0b523769ebb9473c60df1b0f70615aa82ebac2c9 Mon Sep 17 00:00:00 2001
From: Joe Perches <joe@perches.com>
Date: Mon, 8 May 2017 15:55:36 -0700
Subject: [PATCH] checkpatch: add ability to find bad uses of vsprintf %p<foo>
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<foo>.
[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 <joe@perches.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: William Roberts <william.c.roberts@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
lib/vsprintf.c | 3 +++
scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 176641cc549d9..2d41de3f98a1c 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 30eeba4f16025..732bb3e2fe9ae 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5663,6 +5663,32 @@ sub process {
}
}
+ # check for vsprintf extension %p<foo> 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 &&
--
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