Re: [PATCH 5.4 000/168] 5.4.25-stable review

Greg Kroah-Hartman
2020-03-11T18:09:46Z

On Tue, Mar 10, 2020 at 04:07:23PM +0100, Holger Hoffstätte wrote:
> On 3/10/20 4:00 PM, Greg Kroah-Hartman wrote:
> > On Tue, Mar 10, 2020 at 03:51:01PM +0100, Holger Hoffstätte wrote:
> > > On 3/10/20 3:35 PM, Greg Kroah-Hartman wrote:
> > > > On Tue, Mar 10, 2020 at 03:02:37PM +0100, Holger Hoffstätte wrote:
> > > > > On 3/10/20 1:37 PM, Greg Kroah-Hartman wrote:
> > > > > > This is the start of the stable review cycle for the 5.4.25 release.
> > > > >
> > > > > This fails to compile due to broken patch 001/168:
> > > > > "block, bfq: get a ref to a group when adding it to a service tree":
> > > > >
> > > > > ..
> > > > > block/bfq-wf2q.c: In function 'bfq_get_entity':
> > > > > ./include/linux/kernel.h:994:51: error: 'struct bfq_group' has no member named 'entity'
> > > > > ..
> > > > >
> > > > > The calls to bfq_get_entity::bfqg_and_blkg_get and bfq_forget_entity::bfqg_and_blkg_put
> > > > > in bfq-wf2q.c need to be wrapped in #ifdef CONFIG_BFQ_GROUP_IOSCHED, otherwise
> > > > > the build will fail when CONFIG_BFQ_GROUP_IOSCHED is not enabled.
> > > > > This horribly error-prone #ifdef mess was finally removed in upstream commit
> > > > > 4d8340d0d4d9. For 5.4 we'll either need that as well or add them back.
> > > >
> > > > Ick, that's a mess.
> > > >
> > > > I'll go drop that patch now, odd that it passed my build tests...
> > >
> > > Uh, please no? It fixes a rather nasty UAF when cgroups are in use.
> > > Please just add the other upstream commit as well, I confirmed it applies
> > > cleanly and fixes the problem.
> >
> > I didn't get that from your email at all, sorry.
> >
> > So, what commits, and in what order, should be applied to 5.4.y at the
> > moment to resolve this issue?
>
> Just add upstream 4d8340d0d4d9 and it should work. Order shouldn't matter
> (built for me either way) unless you want to follow upstream, in which case
> it should come before "get a ref to a group..". Easy :)

Ok, I've added both back now, and to the 5.5.y tree as well. Hopefully
that should resolve these build issues.

thanks,

greg k-h