Hi Dan, On Wed, Jan 15, 2020, Dan Carpenter wrote: > Syzbot managed to trigger a use after free "KASAN: use-after-free Write > in hci_sock_bind". I have reviewed the code manually and one possibly > cause I have found is that we are not holding lock_sock(sk) when we do > the hci_dev_put(hdev) in hci_sock_release(). My theory is that the bind > and the release are racing against each other which results in this use > after free. > > Reported-by: syzbot+eba992608adf3d796bcc@xxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > --- > Not tested! Please review very very carefully! > > I feel like maybe someone should audit the (struct proto_ops)->release() > functions because there may be similar bugs to this in other drivers. > > net/bluetooth/hci_sock.c | 3 +++ > 1 file changed, 3 insertions(+) The patch looks correct to me since it's following the same locking conventions as all the other socket callbacks in hci_sock.c. I also verified that it doesn't cause regressions in the various socket testers we have in user space BlueZ (e.g. tools/l2cap-tester). The patch is now applied to the bluetooth-next tree. Thanks! Johan
