linux-kernel - [PATCH v5 3/4] checkpatch: Suggest kmalloc

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Message-Id: <20251122014304.3417954-3-kees@kernel.org>
Date: Fri, 21 Nov 2025 17:42:59 -0800
From: Kees Cook <kees@...nel.org>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Kees Cook <kees@...nel.org>,
	Andy Whitcroft <apw@...onical.com>,
	Joe Perches <joe@...ches.com>,
	Dwaipayan Ray <dwaipayanray1@...il.com>,
	Lukas Bulwahn <lukas.bulwahn@...il.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Miguel Ojeda <ojeda@...nel.org>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Matthew Wilcox <willy@...radead.org>,
	Christoph Lameter <cl@...ux.com>,
	Marco Elver <elver@...gle.com>,
	Vegard Nossum <vegard.nossum@...cle.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Harry Yoo <harry.yoo@...cle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Jann Horn <jannh@...gle.com>,
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	llvm@...ts.linux.dev
Subject: [PATCH v5 3/4] checkpatch: Suggest kmalloc_obj family for sizeof allocations

To support shifting away from sized allocation towards typed
allocations, suggest the kmalloc_obj family of macros when a sizeof() is
present in the argument lists.

Signed-off-by: Kees Cook <kees@...nel.org>
---
Cc: Andy Whitcroft <apw@...onical.com>
Cc: Joe Perches <joe@...ches.com>
Cc: Dwaipayan Ray <dwaipayanray1@...il.com>
Cc: Lukas Bulwahn <lukas.bulwahn@...il.com>
---
 scripts/checkpatch.pl | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d58ca9655ab7..a8cdfb502ccc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -7258,17 +7258,42 @@ sub process {
 			    "Prefer $3(sizeof(*$1)...) over $3($4...)\n" . $herecurr);
 		}
 
-# check for (kv|k)[mz]alloc with multiplies that could be kmalloc_array/kvmalloc_array/kvcalloc/kcalloc
+# check for (kv|k)[mz]alloc that could be kmalloc_obj/kvmalloc_obj/kzalloc_obj/kvzalloc_obj
+		if ($perl_version_ok &&
+		    defined $stat &&
+		    $stat =~ /^\+\s*($Lval)\s*\=\s*(?:$balanced_parens)?\s*((?:kv|k)[mz]alloc)\s*\(\s*($FuncArg)\s*,/) {
+			my $oldfunc = $3;
+			my $a1 = $4;
+			my $newfunc = "kmalloc_obj";
+			$newfunc = "kvmalloc_obj" if ($oldfunc eq "kvmalloc");
+			$newfunc = "kvzalloc_obj" if ($oldfunc eq "kvzalloc");
+			$newfunc = "kzalloc_obj" if ($oldfunc eq "kzalloc");
+
+			if ($a1 =~ s/^sizeof\s*\S\(?([^\)]*)\)?$/$1/) {
+				my $cnt = statement_rawlines($stat);
+				my $herectx = get_stat_here($linenr, $cnt, $here);
+
+				if (WARN("ALLOC_WITH_SIZEOF",
+					 "Prefer $newfunc over $oldfunc with sizeof\n" . $herectx) &&
+				    $cnt == 1 &&
+				    $fix) {
+					$fixed[$fixlinenr] =~ s/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*((?:kv|k)[mz]alloc)\s*\(\s*($FuncArg)\s*,/$1 = $newfunc($a1,/;
+				}
+			}
+		}
+
+
+# check for (kv|k)[mz]alloc with multiplies that could be kmalloc_objs/kvmalloc_objs/kzalloc_objs/kvzalloc_objs
 		if ($perl_version_ok &&
 		    defined $stat &&
 		    $stat =~ /^\+\s*($Lval)\s*\=\s*(?:$balanced_parens)?\s*((?:kv|k)[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)\s*,/) {
 			my $oldfunc = $3;
 			my $a1 = $4;
 			my $a2 = $10;
-			my $newfunc = "kmalloc_array";
-			$newfunc = "kvmalloc_array" if ($oldfunc eq "kvmalloc");
-			$newfunc = "kvcalloc" if ($oldfunc eq "kvzalloc");
-			$newfunc = "kcalloc" if ($oldfunc eq "kzalloc");
+			my $newfunc = "kmalloc_objs";
+			$newfunc = "kvmalloc_objs" if ($oldfunc eq "kvmalloc");
+			$newfunc = "kvzalloc_objs" if ($oldfunc eq "kvzalloc");
+			$newfunc = "kzalloc_objs" if ($oldfunc eq "kzalloc");
 			my $r1 = $a1;
 			my $r2 = $a2;
 			if ($a1 =~ /^sizeof\s*\S/) {
@@ -7284,7 +7309,9 @@ sub process {
 					 "Prefer $newfunc over $oldfunc with multiply\n" . $herectx) &&
 				    $cnt == 1 &&
 				    $fix) {
-					$fixed[$fixlinenr] =~ s/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*((?:kv|k)[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/$1 . ' = ' . "$newfunc(" . trim($r1) . ', ' . trim($r2)/e;
+					my $sized = trim($r2);
+					$sized =~ s/^sizeof\s*\S\(?([^\)]*)\)?$/$1/;
+					$fixed[$fixlinenr] =~ s/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*((?:kv|k)[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/$1 . ' = ' . "$newfunc(" . $sized . ', ' . trim($r1)/e;
 				}
 			}
 		}
-- 
2.34.1