Re: [master][krogoth][PATCH 1/2] qemu: Security fix CVE-2016-2857

[Joshua G Lock <joshua.g.lock@linux.intel.com>]

On Wed, 2016-05-04 at 10:52 +0100, Joshua G Lock wrote:
> Hi Armin,
> 
> On Thu, 2016-04-28 at 11:23 -0700, Armin Kuster wrote:
> > 
> > From: Armin Kuster <akuster@mvista.com>
> > 
> I've been seeing:
> 
> "qemu: uncaught target signal 11 (Segmentation fault) - core dumped"
> 
> when trying to build gobject-introspection for qemux86 recently and
> narrowed it down to this change, if I revert this patch the use of
> qemu-native by gobject-introspection no longer causes a segmentation
> fault.
> 
> Are we missing some related patches for this CVE fix? I haven't dug
> into the details, but noticed that Fedora's CVE-2016-2857 diffstat[1]
> is much larger than ours[2].

If I apply the 5 patches from Fedora's CVE-2016-2857 fix (with our
patch reverted) qemu-native's use during a gobject-introspection build
no longer causes segmentation faults.

I've sent a patch proposing an upgrade to 2.5.1 for krogoth and master,
which includes the 5 patch series mentioned above and several other
fixes.

Regards,

Joshua

> 1. http://pkgs.fedoraproject.org/cgit/rpms/qemu.git/commit/?id=54cb13
> 01
> c61f0be7b96e343902bb09be081b34fe
> 2. http://git.openembedded.org/openembedded-core/commit/?id=d1b972a55
> c5
> 9a3f3336b3ebd309532dc204ea97b
> 
> > 
> > ---
> >  .../recipes-devtools/qemu/qemu/CVE-2016-2857.patch | 51
> > ++++++++++++++++++++++
> >  meta/recipes-devtools/qemu/qemu_2.5.0.bb           |  1 +
> >  2 files changed, 52 insertions(+)
> >  create mode 100644 meta/recipes-devtools/qemu/qemu/CVE-2016-
> > 2857.patch
> > 
> > diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2016-2857.patch
> > b/meta/recipes-devtools/qemu/qemu/CVE-2016-2857.patch
> > new file mode 100644
> > index 0000000..73cfa2a
> > --- /dev/null
> > +++ b/meta/recipes-devtools/qemu/qemu/CVE-2016-2857.patch
> > @@ -0,0 +1,51 @@
> > +From 362786f14a753d8a5256ef97d7c10ed576d6572b Mon Sep 17 00:00:00
> > 2001
> > +From: Prasad J Pandit <pjp@fedoraproject.org>
> > +Date: Wed, 2 Mar 2016 17:29:58 +0530
> > +Subject: [PATCH] net: check packet payload length
> > +
> > +While computing IP checksum, 'net_checksum_calculate' reads
> > +payload length from the packet. It could exceed the given 'data'
> > +buffer size. Add a check to avoid it.
> > +
> > +Reported-by: Liu Ling <liuling-it@360.cn>
> > +Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> > +Signed-off-by: Jason Wang <jasowang@redhat.com>
> > +
> > +Upstream-Status: Backport
> > +CVE: CVE-2016-2857
> > +
> > +http://git.qemu.org/?p=qemu.git;a=commit;h=362786f14a753d8a5256ef9
> > 7d
> > 7c10ed576d6572b
> > +Signed-off-by: Armin Kuster <akuster@mvista.com>
> > +
> > +---
> > + net/checksum.c | 10 ++++++++--
> > + 1 file changed, 8 insertions(+), 2 deletions(-)
> > +
> > +Index: qemu-2.5.0/net/checksum.c
> > +==================================================================
> > =
> > +--- qemu-2.5.0.orig/net/checksum.c
> > ++++ qemu-2.5.0/net/checksum.c
> > +@@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *dat
> > +     int hlen, plen, proto, csum_offset;
> > +     uint16_t csum;
> > + 
> > ++    /* Ensure data has complete L2 & L3 headers. */
> > ++    if (length < 14 + 20) {
> > ++        return;
> > ++    }
> > ++
> > +     if ((data[14] & 0xf0) != 0x40)
> > + 	return; /* not IPv4 */
> > +     hlen  = (data[14] & 0x0f) * 4;
> > +@@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *dat
> > + 	return;
> > +     }
> > + 
> > +-    if (plen < csum_offset+2)
> > +-	return;
> > ++    if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
> > ++        return;
> > ++    }
> > + 
> > +     data[14+hlen+csum_offset]   = 0;
> > +     data[14+hlen+csum_offset+1] = 0;
> > diff --git a/meta/recipes-devtools/qemu/qemu_2.5.0.bb
> > b/meta/recipes-
> > devtools/qemu/qemu_2.5.0.bb
> > index e9d9a8d..7622386 100644
> > --- a/meta/recipes-devtools/qemu/qemu_2.5.0.bb
> > +++ b/meta/recipes-devtools/qemu/qemu_2.5.0.bb
> > @@ -11,6 +11,7 @@ SRC_URI += "file://configure-fix-Darwin-target-de
> > te
> > ction.patch \
> >              file://CVE-2016-2197.patch \
> >              file://CVE-2016-2198.patch \
> >              file://pathlimit.patch \
> > +            file://CVE-2016-2857.patch \
> >             "
> >  SRC_URI_prepend = "http://wiki.qemu-project.org/download/${BP}.tar
> > .b
> > z2"
> >  SRC_URI[md5sum] = "f469f2330bbe76e3e39db10e9ac4f8db"
> > -- 
> > 2.3.5
> >