Re: [syzbot] KASAN: use-after-free Read in bdev_evict_inode

[Christoph Hellwig]

On Sun, Aug 15, 2021 at 09:49:30PM +0800, Hillf Danton wrote:
> After putting bdi in wb_exit(), wb->bdi is no longer stable. To fix the uaf,
> add the WB_put bit to avoid derefering a unstable pointer.
> 
> Only for thoughts.

This doesn't help with the fact that the bdi needs to be alive
until after inode_detach_wb is called.  I posted a patch for that last
week, although I'm about to post a v2 as there are more lingering issues
in this area.