Re: [PATCH -rc] workqueue: Reimplement UAF fix to avoid lockdep worning

[Imre Deak]

On Tue, Jun 04, 2024 at 08:20:53AM -0700, Dan Williams wrote:
> Imre Deak wrote:
> > Hi,
> > 
> > [Sorry for the previous message, resending it now
> >  with proper In-reply-to: header added.]
> > 
> > I see a similar issue, a corruption in the lock_keys_hash while
> > alloc_workqueue()->lockdep_register_key() iterates it, see [1] for the
> > stacktrace.
> > 
> > Not sure if related or even will solve [1], but [2] will revert
> > 
> > commit 7e89efc6e9e4 ("PCI: Lock upstream bridge for pci_reset_function()")
> > 
> > which does
> > 
> > lockdep_register_key(&dev->cfg_access_key);
> > 
> > in pci_device_add() and doesn't unregister the key when the pci device is
> > removed (and potentially freed); so basically 7e89efc6e9e4 was missing a
> > 
> > lockdep_unregister_key();
> > 
> > in pci_destroy_dev().
> > 
> > Based on the above I wonder if 7e89efc6e9e4 could also lead to the
> > corruption of lock_keys_hash after a pci device is removed.o
> 
> Are you running with the revert applied and still seeing issues?

The revert is not yet applied and so [1] happened with a kernel
containing 7e89efc6e9e4.

[1] https://intel-gfx-ci.01.org/tree/drm-tip/IGT_7875/bat-atsm-1/dmesg0.txt