2023-09-22 20:21:18

by Kees Cook

Subject: [PATCH] input: Annotate struct evdev_client 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 evdev_client.

[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]>
---
drivers/input/evdev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 95f90699d2b1..51e0c4954600 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -50,7 +50,7 @@ struct evdev_client {
bool revoked;
unsigned long *evmasks[EV_CNT];
unsigned int bufsize;
- struct input_event buffer[];
+ struct input_event buffer[] __counted_by(bufsize);
};

static size_t evdev_get_mask_cnt(unsigned int type)
--
2.34.1

2023-09-23 08:29:46

by Gustavo A. R. Silva

Subject: Re: [PATCH] input: Annotate struct evdev_client 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 evdev_client.
>
> [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

> ---
> drivers/input/evdev.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index 95f90699d2b1..51e0c4954600 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -50,7 +50,7 @@ struct evdev_client {
> bool revoked;
> unsigned long *evmasks[EV_CNT];
> unsigned int bufsize;
> - struct input_event buffer[];
> + struct input_event buffer[] __counted_by(bufsize);
> };
>
> static size_t evdev_get_mask_cnt(unsigned int type)

2023-09-30 17:40:26

by Dmitry Torokhov

Subject: Re: [PATCH] input: Annotate struct evdev_client with __counted_by

On Fri, Sep 22, 2023 at 10:50:28AM -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 evdev_client.
>
> [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