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 <mche...@kernel.org> Cc: Hans Verkuil <hverkuil-ci...@xs4all.nl> Cc: lijian <lij...@yulong.com> Cc: linux-me...@vger.kernel.org Signed-off-by: Kees Cook <keesc...@chromium.org> --- 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
