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") 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); + return; + } + if (ev->status) { hci_conn_del(hcon); hci_dev_unlock(hdev); The value of 'hcon->amp_mgr' getting NULL due to hci_conn_hash_lookup_handle call , and there is not any checks there for the members of hcon, which enables hci_phy_link_complete_evt() to dereference 'hcon->amp_mgr' as NULL. please suggest improvements to this patch. Regards, Anmol
