gnu: QEMU: Fix CVE-2018-11806.

* gnu/packages/patches/qemu-CVE-2018-11806.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/virtualization.scm (qemu)[source]: Use it.

gnu/local.mk

@@ -1073,6 +1073,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-unittest2-remove-argparse.patch	\
   %D%/packages/patches/python-waitress-fix-tests.patch		\
   %D%/packages/patches/qemu-glibc-2.27.patch 			\
+  %D%/packages/patches/qemu-CVE-2018-11806.patch 		\
   %D%/packages/patches/qt4-ldflags.patch			\
   %D%/packages/patches/qtbase-use-TZDIR.patch			\
   %D%/packages/patches/qtscript-disable-tests.patch		\

gnu/packages/patches/qemu-CVE-2018-11806.patch

@@ -0,0 +1,105 @@
+Fix CVE-2018-11806:
+
+https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg01012.html
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-11806
+
+Patch copied from upstream source repository:
+
+https://git.qemu.org/?p=qemu.git;a=commitdiff;h=864036e251f54c99d31df124aad7f34f01f5344c
+
+From 864036e251f54c99d31df124aad7f34f01f5344c Mon Sep 17 00:00:00 2001
+From: Prasad J Pandit <pjp@fedoraproject.org>
+Date: Tue, 5 Jun 2018 23:38:35 +0530
+Subject: [PATCH] slirp: correct size computation while concatenating mbuf
+
+While reassembling incoming fragmented datagrams, 'm_cat' routine
+extends the 'mbuf' buffer, if it has insufficient room. It computes
+a wrong buffer size, which leads to overwriting adjacent heap buffer
+area. Correct this size computation in m_cat.
+
+Reported-by: ZDI Disclosures <zdi-disclosures@trendmicro.com>
+Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
+Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
+---
+ slirp/mbuf.c | 11 +++++------
+ slirp/mbuf.h |  8 +++-----
+ 2 files changed, 8 insertions(+), 11 deletions(-)
+
+diff --git a/slirp/mbuf.c b/slirp/mbuf.c
+index 5ff24559fd..18cbf759a7 100644
+--- a/slirp/mbuf.c
++++ b/slirp/mbuf.c
+@@ -138,7 +138,7 @@ m_cat(struct mbuf *m, struct mbuf *n)
+ 	 * If there's no room, realloc
+ 	 */
+ 	if (M_FREEROOM(m) < n->m_len)
+-		m_inc(m,m->m_size+MINCSIZE);
++		m_inc(m, m->m_len + n->m_len);
+ 
+ 	memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
+ 	m->m_len += n->m_len;
+@@ -147,7 +147,7 @@ m_cat(struct mbuf *m, struct mbuf *n)
+ }
+ 
+ 
+-/* make m size bytes large */
++/* make m 'size' bytes large from m_data */
+ void
+ m_inc(struct mbuf *m, int size)
+ {
+@@ -158,12 +158,12 @@ m_inc(struct mbuf *m, int size)
+ 
+         if (m->m_flags & M_EXT) {
+ 	  datasize = m->m_data - m->m_ext;
+-          m->m_ext = g_realloc(m->m_ext, size);
++	  m->m_ext = g_realloc(m->m_ext, size + datasize);
+ 	  m->m_data = m->m_ext + datasize;
+         } else {
+ 	  char *dat;
+ 	  datasize = m->m_data - m->m_dat;
+-          dat = g_malloc(size);
++	  dat = g_malloc(size + datasize);
+ 	  memcpy(dat, m->m_dat, m->m_size);
+ 
+ 	  m->m_ext = dat;
+@@ -171,8 +171,7 @@ m_inc(struct mbuf *m, int size)
+ 	  m->m_flags |= M_EXT;
+         }
+ 
+-        m->m_size = size;
+-
++        m->m_size = size + datasize;
+ }
+ 
+ 
+diff --git a/slirp/mbuf.h b/slirp/mbuf.h
+index 893601ff9d..33b84485d6 100644
+--- a/slirp/mbuf.h
++++ b/slirp/mbuf.h
+@@ -33,8 +33,6 @@
+ #ifndef MBUF_H
+ #define MBUF_H
+ 
+-#define MINCSIZE 4096	/* Amount to increase mbuf if too small */
+-
+ /*
+  * Macros for type conversion
+  * mtod(m,t) -	convert mbuf pointer to data pointer of correct type
+@@ -72,11 +70,11 @@ struct mbuf {
+ 	struct	mbuf *m_prevpkt;	/* Flags aren't used in the output queue */
+ 	int	m_flags;		/* Misc flags */
+ 
+-	int	m_size;			/* Size of data */
++	int	m_size;			/* Size of mbuf, from m_dat or m_ext */
+ 	struct	socket *m_so;
+ 
+-	caddr_t	m_data;			/* Location of data */
+-	int	m_len;			/* Amount of data in this mbuf */
++	caddr_t	m_data;			/* Current location of data */
++	int	m_len;			/* Amount of data in this mbuf, from m_data */
+ 
+ 	Slirp *slirp;
+ 	bool	resolution_requested;
+-- 
+2.17.1
+

gnu/packages/virtualization.scm

@@ -98,6 +98,7 @@
              (method url-fetch)
              (uri (string-append "https://download.qemu.org/qemu-"
                                  version ".tar.xz"))
+             (patches (search-patches "qemu-CVE-2018-11806.patch"))
              (sha256
               (base32
                "1z66spkm1prvhbq7h5mfnp0i6mmamsb938fqmdfvyrgzc7rh34z6"))))