On Sun, Aug 30, 2020 at 05:56:23PM +0530, Anmol Karn wrote: > On Sun, Aug 30, 2020 at 11:19:17AM +0200, Greg KH wrote: > > On Sat, Aug 29, 2020 at 10:27:12PM +0530, Anmol Karn wrote: > > > Fix null pointer deref in hci_phy_link_complete_evt, there was no > > > checking there for the hcon->amp_mgr->l2cap_conn->hconn, and also > > > in hci_cmd_work, for hdev->sent_cmd. > > > > > > To fix this issue Add pointer checking in hci_cmd_work and > > > hci_phy_link_complete_evt. > > > [Linux-next-20200827] > > > > > > This patch corrected some mistakes from previous patch. > > > > > > Reported-by: syzbot+0bef568258653cff272f@xxxxxxxxxxxxxxxxxxxxxxxxx > > > Link: https://syzkaller.appspot.com/bug?id=0d93140da5a82305a66a136af99b088b75177b99 > > > Signed-off-by: Anmol Karn <anmol.karan123@xxxxxxxxx> > > > --- > > > net/bluetooth/hci_core.c | 5 ++++- > > > net/bluetooth/hci_event.c | 4 ++++ > > > 2 files changed, 8 insertions(+), 1 deletion(-) > > > > > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c > > > index 68bfe57b6625..996efd654e7a 100644 > > > --- a/net/bluetooth/hci_core.c > > > +++ b/net/bluetooth/hci_core.c > > > @@ -4922,7 +4922,10 @@ static void hci_cmd_work(struct work_struct *work) > > > > > > kfree_skb(hdev->sent_cmd); > > > > > > - hdev->sent_cmd = skb_clone(skb, GFP_KERNEL); > > > + if (hdev->sent_cmd) { > > > + hdev->sent_cmd = skb_clone(skb, GFP_KERNEL); > > > + } > > > > How can sent_cmd be NULL here? Are you sure something previous to this > > shouldn't be fixed instead? > > Sir, sent_cmd was freed before this condition check, thats why i checked it, But it can not be NULL at that point in time, as nothing set it to NULL, correct? > i think i should check it before the free of hdev->sent_cmd like, > > if (hdev->sent_cmd) > kfree_skb(hdev->sent_cmd); No, that's not needed. What is the problem with these lines that you are trying to solve? > > > + > > > if (hdev->sent_cmd) { > > > if (hci_req_status_pend(hdev)) > > > hci_dev_set_flag(hdev, HCI_CMD_PENDING); > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c > > > index 4b7fc430793c..1e7d9bee9111 100644 > > > --- a/net/bluetooth/hci_event.c > > > +++ b/net/bluetooth/hci_event.c > > > @@ -4941,6 +4941,10 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev, > > > hci_dev_unlock(hdev); > > > return; > > > } > > > + if (!(hcon->amp_mgr->l2cap_conn->hcon)) { > > > + hci_dev_unlock(hdev); > > > + return; > > > + } > > > > How can this be triggered? > > syzbot showed that this line is accessed irrespective of the null value it contains, so added a > pointer check for that. But does hcon->amp_mgr->l2cap_conn->hcon become NULL here? thanks, greg k-h
