linux-kernel - [PATCH] checkpatch: Add --strict test for kmalloc/kzalloc with multiply

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Date:	Tue, 13 May 2014 16:48:49 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andy Whitcroft <apw@...onical.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] checkpatch: Add --strict test for kmalloc/kzalloc with
 multiply

Protect against sizeof overflows by preferring
kmalloc_array and kcalloc to kmalloc/kzalloc
with a sizeof multiply.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 scripts/checkpatch.pl | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e7ff52a..33eb71f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4378,6 +4378,20 @@ sub process {
 			    "Prefer $3(sizeof(*$1)...) over $3($4...)\n" . $herecurr);
 		}
 
+# check for k[mz]alloc with multiplies that could be kmalloc_array/kcalloc
+		if ($^V && $^V ge 5.10.0 &&
+		    $line =~ /\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/) {
+			my $oldfunc = $3;
+			my $a1 = $4;
+			my $a2 = $10;
+			my $newfunc = "kmalloc_array";
+			$newfunc = "kcalloc" if ($oldfunc eq "kzalloc");
+			if ($a1 =~ /^sizeof\s*\S/ || $a2 =~ /^sizeof\s*\S/) {
+				CHK("ALLOC_WITH_MULTIPLY",
+				    "Prefer $newfunc over $oldfunc with multiply\n" . $herecurr);
+			}
+		}
+
 # check for krealloc arg reuse
 		if ($^V && $^V ge 5.10.0 &&
 		    $line =~ /\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*krealloc\s*\(\s*\1\s*,/) {


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