[next] net: wwan: t7xx: Add __counted_by for struct t7xx_fsm_event and use struct_size()
Commit Message
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 via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).
While there, use struct_size() helper, instead of the open-coded
version, to calculate the size for the allocation of the whole
flexible structure, including of course, the flexible-array member.
This code was found with the help of Coccinelle, and audited and
fixed manually.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/net/wwan/t7xx/t7xx_state_monitor.c | 3 ++-
drivers/net/wwan/t7xx/t7xx_state_monitor.h | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
Comments
On Mon, Oct 09, 2023 at 03:46:18PM -0600, Gustavo A. R. Silva 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> While there, use struct_size() helper, instead of the open-coded
> version, to calculate the size for the allocation of the whole
> flexible structure, including of course, the flexible-array member.
>
> This code was found with the help of Coccinelle, and audited and
> fixed manually.
>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Looks right to me.
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> drivers/net/wwan/t7xx/t7xx_state_monitor.c | 3 ++-
> drivers/net/wwan/t7xx/t7xx_state_monitor.h | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wwan/t7xx/t7xx_state_monitor.c b/drivers/net/wwan/t7xx/t7xx_state_monitor.c
> index 80edb8e75a6a..0bc97430211b 100644
> --- a/drivers/net/wwan/t7xx/t7xx_state_monitor.c
> +++ b/drivers/net/wwan/t7xx/t7xx_state_monitor.c
> @@ -445,7 +445,8 @@ int t7xx_fsm_append_event(struct t7xx_fsm_ctl *ctl, enum t7xx_fsm_event_state ev
> return -EINVAL;
> }
>
> - event = kmalloc(sizeof(*event) + length, in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
> + event = kmalloc(struct_size(event, data, length),
> + in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
> if (!event)
> return -ENOMEM;
>
> diff --git a/drivers/net/wwan/t7xx/t7xx_state_monitor.h b/drivers/net/wwan/t7xx/t7xx_state_monitor.h
> index b6e76f3903c8..b0b3662ae6d7 100644
> --- a/drivers/net/wwan/t7xx/t7xx_state_monitor.h
> +++ b/drivers/net/wwan/t7xx/t7xx_state_monitor.h
> @@ -102,7 +102,7 @@ struct t7xx_fsm_event {
> struct list_head entry;
> enum t7xx_fsm_event_state event_id;
> unsigned int length;
> - unsigned char data[];
> + unsigned char data[] __counted_by(length);
> };
>
> struct t7xx_fsm_command {
> --
> 2.34.1
>
>
@@ -445,7 +445,8 @@ int t7xx_fsm_append_event(struct t7xx_fsm_ctl *ctl, enum t7xx_fsm_event_state ev
return -EINVAL;
}
- event = kmalloc(sizeof(*event) + length, in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
+ event = kmalloc(struct_size(event, data, length),
+ in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
if (!event)
return -ENOMEM;
@@ -102,7 +102,7 @@ struct t7xx_fsm_event {
struct list_head entry;
enum t7xx_fsm_event_state event_id;
unsigned int length;
- unsigned char data[];
+ unsigned char data[] __counted_by(length);
};
struct t7xx_fsm_command {