On Sat, Sep 12, 2020 at 02:40:28PM +0530, Anmol Karn wrote: > On Thu, Sep 10, 2020 at 01:49:18PM +0300, Dan Carpenter wrote: > > On Thu, Sep 10, 2020 at 10:04:24AM +0530, Anmol Karn wrote: > > > Prevent hci_phy_link_complete_evt() from dereferencing 'hcon->amp_mgr' > > > as NULL. Fix it by adding pointer check for it. > > > > > > Reported-and-tested-by: syzbot+0bef568258653cff272f@xxxxxxxxxxxxxxxxxxxxxxxxx > > > Link: https://syzkaller.appspot.com/bug?extid=0bef568258653cff272f > > > Signed-off-by: Anmol Karn <anmol.karan123@xxxxxxxxx> > > > --- > > > net/bluetooth/hci_event.c | 5 +++++ > > > 1 file changed, 5 insertions(+) > > > > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c > > > index 4b7fc430793c..871e16804433 100644 > > > --- a/net/bluetooth/hci_event.c > > > +++ b/net/bluetooth/hci_event.c > > > @@ -4936,6 +4936,11 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev, > > > return; > > > } > > > > > > + if (IS_ERR_OR_NULL(hcon->amp_mgr)) { > > > > It can't be an error pointer. Shouldn't we call hci_conn_del() on this > > path? Try to find the Fixes tag to explain how this bug was introduced. > > > > (Don't rush to send a v2. The patch requires quite a bit more digging > > and detective work before it is ready). > > > > > + hci_dev_unlock(hdev); > > > + return; > > > + } > > > + > > > if (ev->status) { > > > hci_conn_del(hcon); > > > hci_dev_unlock(hdev); > > > > regards, > > dan carpenter > > > > Sir, > > I need little advice in continuing with this Patch, > > I have looked into the Bisected logs and the problem occurs from this commit: > > 941992d29447 ("ethernet: amd: use IS_ENABLED() instead of checking for built-in or module") > That's just the patch which made the code testable by syzbot. It didn't introduce the bug. > > Here is a diff of patch which i modified from last patch, > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c > index 4b7fc430793c..6ce435064e0b 100644 > --- a/net/bluetooth/hci_event.c > +++ b/net/bluetooth/hci_event.c > @@ -4936,6 +4936,12 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev, > return; > } > > + if (!hcon->amp_mgr) { > + hci_conn_del(hcon); > + hci_dev_unlock(hdev); I have no idea if calling hci_conn_del() is really the correct, thing. I don't know the code at all. Anyway, do some research and figure out for sure what the correct thing is. Also look for similar bugs in other places where hcon->amp_mgr is dereferenced. For example, amp_read_loc_assoc_final_data() seems to have a similar bug. regards, dan carpenter
