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 <mchehab@xxxxxxxxxx>
Cc: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Cc: lijian <lijian@xxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
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);
};
/**
