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 v4l2_subscribed_event.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.
[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: lijian <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
drivers/media/v4l2-core/v4l2-event.c | 2 +-
include/media/v4l2-event.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index c5ce9f11ad7b..3898ff7edddb 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -238,6 +238,7 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
if (!sev)
return -ENOMEM;
+ sev->elems = elems;
for (i = 0; i < elems; i++)
sev->events[i].sev = sev;
sev->type = sub->type;
@@ -245,7 +246,6 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
sev->flags = sub->flags;
sev->fh = fh;
sev->ops = ops;
- sev->elems = elems;
mutex_lock(&fh->subscribe_lock);
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 4ffa914ade3a..3a0e2588361c 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -78,7 +78,7 @@ struct v4l2_subscribed_event {
unsigned int elems;
unsigned int first;
unsigned int in_use;
- struct v4l2_kevent events[];
+ struct v4l2_kevent events[] __counted_by(elems);
};
/**
--
2.34.1
On 9/22/23 11:49, 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 v4l2_subscribed_event.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Mauro Carvalho Chehab <[email protected]>
> Cc: Hans Verkuil <[email protected]>
> Cc: lijian <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Thanks
--
Gustavo
> ---
> drivers/media/v4l2-core/v4l2-event.c | 2 +-
> include/media/v4l2-event.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
> index c5ce9f11ad7b..3898ff7edddb 100644
> --- a/drivers/media/v4l2-core/v4l2-event.c
> +++ b/drivers/media/v4l2-core/v4l2-event.c
> @@ -238,6 +238,7 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
> sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
> if (!sev)
> return -ENOMEM;
> + sev->elems = elems;
> for (i = 0; i < elems; i++)
> sev->events[i].sev = sev;
> sev->type = sub->type;
> @@ -245,7 +246,6 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
> sev->flags = sub->flags;
> sev->fh = fh;
> sev->ops = ops;
> - sev->elems = elems;
>
> mutex_lock(&fh->subscribe_lock);
>
> diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
> index 4ffa914ade3a..3a0e2588361c 100644
> --- a/include/media/v4l2-event.h
> +++ b/include/media/v4l2-event.h
> @@ -78,7 +78,7 @@ struct v4l2_subscribed_event {
> unsigned int elems;
> unsigned int first;
> unsigned int in_use;
> - struct v4l2_kevent events[];
> + struct v4l2_kevent events[] __counted_by(elems);
> };
>
> /**
On Fri, 22 Sep 2023 10:49:52 -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 v4l2_subscribed_event.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [...]
Since this is a trivial change and it's been 2 week without further
discussion, I'll snag this patch.
Applied to for-next/hardening, thanks!
[1/1] media: v4l2-event: Annotate struct v4l2_subscribed_event with __counted_by
https://git.kernel.org/kees/c/b1a20bbd4687
Take care,
--
Kees Cook
On 06/10/2023 22:28, Kees Cook wrote:
> On Fri, 22 Sep 2023 10:49:52 -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 v4l2_subscribed_event.
>> Additionally, since the element count member must be set before accessing
>> the annotated flexible array member, move its initialization earlier.
>>
>> [...]
>
> Since this is a trivial change and it's been 2 week without further
> discussion, I'll snag this patch.
Ah, I picked this up for media as well. Same for the other patch.
You should have gotten an email from patchwork on Oct 3 that it was accepted.
I think I should be more pro-active and reply when I pick up patches from
non-media developers instead of relying on patchwork. It seems that it is
easy to miss emails from patchwork.
Regards,
Hans
>
> Applied to for-next/hardening, thanks!
>
> [1/1] media: v4l2-event: Annotate struct v4l2_subscribed_event with __counted_by
> https://git.kernel.org/kees/c/b1a20bbd4687
>
> Take care,
>
On Sat, Oct 07, 2023 at 11:21:26AM +0200, Hans Verkuil wrote:
> On 06/10/2023 22:28, Kees Cook wrote:
> > On Fri, 22 Sep 2023 10:49:52 -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 v4l2_subscribed_event.
> >> Additionally, since the element count member must be set before accessing
> >> the annotated flexible array member, move its initialization earlier.
> >>
> >> [...]
> >
> > Since this is a trivial change and it's been 2 week without further
> > discussion, I'll snag this patch.
>
> Ah, I picked this up for media as well. Same for the other patch.
> You should have gotten an email from patchwork on Oct 3 that it was accepted.
>
> I think I should be more pro-active and reply when I pick up patches from
> non-media developers instead of relying on patchwork. It seems that it is
> easy to miss emails from patchwork.
Ah! Thanks for reminding me. I'll drop them from the hardening tree. :)
-Kees
--
Kees Cook