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

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Date:   Mon, 29 Oct 2018 10:13:02 +0300
From:   Anatoly Trosinenko <anatoly.trosinenko@...il.com>
To:     nicolas.pitre@...aro.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: Cramfs: "unable to handle kernel paging request" when reading a
 file from a fuzzed FS image

> 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
пн, 29 окт. 2018 г. в 6:43, Nicolas Pitre <nicolas.pitre@...aro.org>:
>
> 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@...-xfstests:~# mount /vtmp
> > root@...-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