2023-09-22 23:25:39

by Kees Cook

Subject: [PATCH] input: mt: Annotate struct input_mt with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct input_mt.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Dmitry Torokhov <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
include/linux/input/mt.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index 3b8580bd33c1..2cf89a538b18 100644
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -47,7 +47,7 @@ struct input_mt {
unsigned int flags;
unsigned int frame;
int *red;
- struct input_mt_slot slots[];
+ struct input_mt_slot slots[] __counted_by(num_slots);
};

static inline void input_mt_set_value(struct input_mt_slot *slot,
--
2.34.1

2023-09-23 08:29:50

by Gustavo A. R. Silva

Subject: Re: [PATCH] input: mt: Annotate struct input_mt with __counted_by

On 9/22/23 11:50, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct input_mt.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Dmitry Torokhov <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks
--
Gustavo

> ---
> include/linux/input/mt.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
> index 3b8580bd33c1..2cf89a538b18 100644
> --- a/include/linux/input/mt.h
> +++ b/include/linux/input/mt.h
> @@ -47,7 +47,7 @@ struct input_mt {
> unsigned int flags;
> unsigned int frame;
> int *red;
> - struct input_mt_slot slots[];
> + struct input_mt_slot slots[] __counted_by(num_slots);
> };
>
> static inline void input_mt_set_value(struct input_mt_slot *slot,

2023-10-01 02:30:56

by Dmitry Torokhov

Subject: Re: [PATCH] input: mt: Annotate struct input_mt with __counted_by

On Fri, Sep 22, 2023 at 10:50:37AM -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct input_mt.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Dmitry Torokhov <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Applied, thank you.

--
Dmitry