Re: linuxnext-2019127 edac warns (was Re: edac KASAN warning in experimental arm64 allmodconfig boot)

[John Garry]

On 28/11/2019 21:12, Robert Richter wrote:
> On 27.11.19 17:07:33, John Garry wrote:
> > [   22.104498] BUG: KASAN: use-after-free in
> > edac_remove_sysfs_mci_device+0x148/0x180
>
> It is triggered in edac_remove_sysfs_mci_device().
>
> device_unregister(&dimm->dev) not only removes the sysfs entry, it
> also frees the dimm struct in dimm_attr_release(). When incrementing
> the loop in mci_for_each_dimm(), the dimm struct is accessed again
> which causes the use-after-free. But, the dimm struct shouln'd be
> released here already.
>
> edac_remove_sysfs_mci_device() should not release the devices at this
> point. We need clean release functions for mci and dimm_info and
> refcounts to protect pdev/dev mappings. And mci_for_each_dimm() must
> be checked how it handles device removals and if it is safe.
>
> Let's see how this can be fixed.
>
> Thanks for reporting the issue.

Fine, and would any fix also deal with the v5.4 mem leak which I 
mentioned also?

Cheers,
John