On Tue, 2021-08-17 at 23:16 -0700, Kees Cook wrote:

On Tue, Aug 17, 2021 at 10:31:32PM -0700, Joe Perches wrote:

quoted

On Tue, 2021-08-17 at 22:08 -0700, Kees Cook wrote:

quoted

As already done in GrapheneOS, add the __alloc_size attribute for
regular kmalloc interfaces, to provide additional hinting for better
bounds checking, assisting CONFIG_FORTIFY_SOURCE and other compiler
optimizations.

[]

quoted

Lastly __alloc_size should probably be added to checkpatch

Oh, yes! Thanks for the reminder.

quoted

Maybe:
---
 scripts/checkpatch.pl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 161ce7fe5d1e5..1a166b5cf3447 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl

@@ -489,7 +489,8 @@ our $Attribute	= qr{

 			____cacheline_aligned|
 			____cacheline_aligned_in_smp|
 			____cacheline_internodealigned_in_smp|
-			__weak
+			__weak|
+			__alloc_size\s*\(\s*\d+\s*(?:,\s*d+\s*){0,5}\)

Why the "{0,5}" bit here? I was expecting just "?". (i.e. it can have
either 1 or 2 arguments.)

You are right.  I misread the doc.  I also missed a \ before the last d.

So that last added line should maybe be: (totally untested btw)

+			__alloc_size\s*\(\s*\d+\s*(?:,\s*\d+\s*)?\)