Hello Marcel, I added some comments into the code about what the kcov_remote calls do and why they were implemented and I also added some reasoning to the commit message. I did not mention in the commit but these functions only run if the kernel is compiled with CONFIG_KCOV. Thank you again for reviewing the patch! -- Tamas On Tue, Jun 7, 2022 at 12:40 PM Tamas Koczka <poprdi@xxxxxxxxxx> wrote: > > Annotate hci_rx_work() with kcov_remote_start() and kcov_remote_stop() > calls, so remote KCOV coverage is collected while processing the rx_q > queue which is the main incoming Bluetooth packet queue. > > Coverage is associated with the thread which created the packet skb. > > The collected extra coverage helps kernel fuzzing efforts in finding > vulnerabilities. > > Signed-off-by: Tamas Koczka <poprdi@xxxxxxxxxx> > --- > Changelog since v1: > - add comment about why kcov_remote functions are called > > v1: https://lore.kernel.org/all/20220517094532.2729049-1-poprdi@xxxxxxxxxx/ > > net/bluetooth/hci_core.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c > index 45c2dd2e1590..0af43844c55a 100644 > --- a/net/bluetooth/hci_core.c > +++ b/net/bluetooth/hci_core.c > @@ -29,6 +29,7 @@ > #include <linux/rfkill.h> > #include <linux/debugfs.h> > #include <linux/crypto.h> > +#include <linux/kcov.h> > #include <linux/property.h> > #include <linux/suspend.h> > #include <linux/wait.h> > @@ -3780,7 +3781,14 @@ static void hci_rx_work(struct work_struct *work) > > BT_DBG("%s", hdev->name); > > - while ((skb = skb_dequeue(&hdev->rx_q))) { > + /* The kcov_remote functions used for collecting packet parsing > + * coverage information from this background thread and associate > + * the coverage with the syscall's thread which originally injected > + * the packet. This helps fuzzing the kernel. > + */ > + for (; (skb = skb_dequeue(&hdev->rx_q)); kcov_remote_stop()) { > + kcov_remote_start_common(skb_get_kcov_handle(skb)); > + > /* Send copy to monitor */ > hci_send_to_monitor(hdev, skb); > > -- > 2.36.1.255.ge46751e96f-goog >
