[Cocci] Weird whitespace behavior?

[Kees Cook]

Hi,

I've been doing some large treewide changes to the allocators, and I
notice that Coccinelle does something odd for a specific case. I have
two scripts, one operating on kmalloc() and one operating on
devm_kmalloc(). They are identical script except for the function
names, however, while kmalloc produces patches like this:

- foo = kmalloc(a * b, gfp);
+ foo = kmalloc_array(a, b, gfp);

the devm_kmalloc one produces:

- foo = devm_kmalloc(handle, a * b, gfp);
+ foo =devm_kmalloc_array(a, b, gfp);

I can't figure out why the space after "=" is missing and have been
manually fixing it up...

-Kees

[Kees Cook]

Post by Kees Cook
Hi,
I've been doing some large treewide changes to the allocators, and I
notice that Coccinelle does something odd for a specific case. I have
two scripts, one operating on kmalloc() and one operating on
devm_kmalloc(). They are identical script except for the function
- foo = kmalloc(a * b, gfp);
+ foo = kmalloc_array(a, b, gfp);
- foo = devm_kmalloc(handle, a * b, gfp);
+ foo =devm_kmalloc_array(a, b, gfp);
I can't figure out why the space after "=" is missing and have been
manually fixing it up...

And while I'm at it... line breaks aren't working like I'd expect:

- collection = kmalloc(sizeof(struct hid_collection) *
- parser->device->collection_size * 2,
GFP_KERNEL);
+ collection = kmalloc(array3_size(sizeof(struct
hid_collection), parser->device->collection_size, 2),
+ GFP_KERNEL);

Why wasn't array3_size() correctly line wrapped?

-Kees

[Julia Lawall]

Post by Kees Cook

Post by Kees Cook
Hi,
I've been doing some large treewide changes to the allocators, and I
notice that Coccinelle does something odd for a specific case. I have
two scripts, one operating on kmalloc() and one operating on
devm_kmalloc(). They are identical script except for the function
- foo = kmalloc(a * b, gfp);
+ foo = kmalloc_array(a, b, gfp);
- foo = devm_kmalloc(handle, a * b, gfp);
+ foo =devm_kmalloc_array(a, b, gfp);
I can't figure out why the space after "=" is missing and have been
manually fixing it up...

I would need your semantic patch to see the problem.

Post by Kees Cook
- collection = kmalloc(sizeof(struct hid_collection) *
- parser->device->collection_size * 2,
GFP_KERNEL);
+ collection = kmalloc(array3_size(sizeof(struct
hid_collection), parser->device->collection_size, 2),
+ GFP_KERNEL);
Why wasn't array3_size() correctly line wrapped?

I think that line breaking only works on the outermost function call.

julia

[SF Markus Elfring]

Post by Kees Cook
I've been doing some large treewide changes to the allocators,

I find your update suggestion “mm: Use overflow helpers in kmalloc_array*()” interesting.

https://lkml.org/lkml/2018/5/31/877
https://patchwork.kernel.org/patch/10442283/
https://lkml.kernel.org/r/<20180601004233.37822-7-***@chromium.org>


It seems that corresponding work became noteworthy news “4.18 Merge window, part 2”.
https://lwn.net/Articles/757187/


Now I am curious on how software evolution will be continued according to such
a transformation pattern.
https://patchwork.kernel.org/project/LKML/list/?state=*&q=alloc_array

Post by Kees Cook
and I notice that Coccinelle does something odd for a specific case.

Will there happen any more evolution in this software area?

Regards,
Markus