Messages in this thread | | | Date | Fri, 18 May 2018 17:28:15 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH] idr: fix invalid ptr dereference on item delete |
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On Fri, May 18, 2018 at 03:31:38PM -0700, Andrew Morton wrote: > On Fri, 18 May 2018 10:50:25 -0700 Matthew Wilcox <willy@infradead.org> wrote: > > If the radix tree underlying the IDR happens to be full and we attempt > > to remove an id which is larger than any id in the IDR, we will call > > __radix_tree_delete() with an uninitialised 'slot' pointer, at which > > point anything could happen. This was easiest to hit with a single entry > > at id 0 and attempting to remove a non-0 id, but it could have happened > > with 64 entries and attempting to remove an id >= 64. > > > > Fixes: 0a835c4f090a ("Reimplement IDR and IDA using the radix tree") > > Reported-by: syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com > > Debugged-by: Roman Kagan <rkagan@virtuozzo.com> > > Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> > > Neither of the changelogs I'm seeing attempt to describe the end-user > impact of the bug. People like to know that so they can decide which > kernel version(s) need patching, so please always remember it.
The problem is that it could be user-triggerable a dozen different ways.
> Looknig at the sysbot report, the impact is at least "privileged user > can trigger a WARN", but I assume there could be worse, > as-yet-undiscovered impacts. So I'm thinking a cc:stable is needed, > yes?
I thought if I used the Fixes: tag it would automatically get picked up. Did I misunderstand? I can imagine many different parts of the kernel that use the IDR could trigger such a warning (although syzbot should probably have tripped over them before now) so I wouldn't downplay it to "only privileged users".
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