[PATCH v6 2/5] checkpatch: Suggest kmalloc_obj family for sizeof allocations

Kees Cook
2025-12-03T23:30:50Z

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@kernel.org>
---
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.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