On Fri, Mar 23, 2018 at 08:21:52AM +0800, Herbert Xu wrote: > On Sat, Mar 10, 2018 at 03:22:31PM -0800, Eric Biggers wrote: > > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > > > If the pcrypt template is used multiple times in an algorithm, then a > > deadlock occurs because all pcrypt instances share the same > > padata_instance, which completes requests in the order submitted. That > > is, the inner pcrypt request waits for the outer pcrypt request while > > the outer request is already waiting for the inner. > > > > Fix this by making pcrypt forbid instantiation if pcrypt appears in the > > underlying ->cra_driver_name. This is somewhat of a hack, but it's a > > simple fix that should be sufficient to prevent the deadlock. > > I'm a bit uneasy with this fix. What if pcrypt is used in the > underlying algorithm as a fallback? Wouldn't it still dead-lock > without triggering this check? > Yep, I think you're right. Steffen, how feasible do you think would it be to make each pcrypt instance use its own padata instance, so different pcrypt instances aren't ordered with respect to each other? Or do you think there is a better solution? This really needs to be fixed; syzbot has hit it over 11000 times already. Eric
