From 54b6b605b9a00f5d93b48734122fa87ae345981e Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 22 Sep 2023 10:49:52 -0700 Subject: [PATCH] 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 Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Signed-off-by: Hans Verkuil --- 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); }; /**