Re: Cramfs: "unable to handle kernel paging request" when reading a file from a fuzzed FS image

[Anatoly Trosinenko]

> How do I populate /vtmp? Mine is empty at this point. I imagine I should
put the cramfs image somewhere on the host, but I'm not that familiar
withkvm.

Oops, forgot to say, it is the /tmp/kvm-xfstests-$USER directory on
the host (it will be created when you first launch kvm-xfstests and it
is "live", i.e. like NFS, not like "pack to ext4 image then boot and
mount").

> Hmmm... It doesn't show up on my test system.

Mounted it on my host Ubuntu 18.10 amd64, executed `cat /mnt/xyz` and
it was "Killed". Maybe it is something freshly added or
arch-dependent...

# uname -a
Linux trosinenko-pc 4.18.0-10-generic #11-Ubuntu SMP Thu Oct 11
15:13:55 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Best regards
Anatoly
ÐÐ, 29 ÐÐÑ. 2018 Ð. Ð 6:43, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>:
>
> On Sun, 28 Oct 2018, Anatoly Trosinenko wrote:
>
> > Hello,
> >
> > When reading a file from a fuzzed cramfs image, unhandled kernel
> > paging request occurs.
>
> Hmmm... It doesn't show up on my test system.
>
> > How to reproduce with kvm-xfstests:
> > 1) Checkout the v4.19 tag, copy x86_64-config-4.14 to .config, perform
> > `make olddefconfig`
> > 2) Enable Cramfs in the config, then compile
> > 3) In the `kvm-xfstests shell` perform:
> >
> > root@kvm-xfstests:~# mount /vtmp
> > root@kvm-xfstests:~# mount /vtmp/cramfs.img /mnt
>
> How do I populate /vtmp? Mine is empty at this point. I imagine I should
> put the cramfs image somewhere on the host, but I'm not that familiar
> withkvm.
>
>
> Nicolas