Commit 54b6b605 authored by Kees Cook's avatar Kees Cook Committed by Hans Verkuil
Browse files

media: v4l2-event: Annotate struct v4l2_subscribed_event 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 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: lijian <lijian@yulong.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
parent d4255578

drivers/media/v4l2-core/v4l2-event.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

include/media/v4l2-event.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

};



/**