gnu: qemu: Add fix for CVE-2015-3209.

* gnu/packages/patches/qemu-CVE-2015-3209.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/qemu.scm (qemu): Add patch.

1 files changed, 49 insertions, 0 deletions

diff --git a/gnu/packages/patches/qemu-CVE-2015-3209.patch b/gnu/packages/patches/qemu-CVE-2015-3209.patch
new file mode 100644
index 0000000000..0bb726698c
--- /dev/null
+++ b/gnu/packages/patches/qemu-CVE-2015-3209.patch
@@ -0,0 +1,49 @@
+From 9f7c594c006289ad41169b854d70f5da6e400a2a Mon Sep 17 00:00:00 2001
+From: Petr Matousek <pmatouse@redhat.com>
+Date: Sun, 24 May 2015 10:53:44 +0200
+Subject: [PATCH] pcnet: force the buffer access to be in bounds during tx
+
+4096 is the maximum length per TMD and it is also currently the size of
+the relay buffer pcnet driver uses for sending the packet data to QEMU
+for further processing. With packet spanning multiple TMDs it can
+happen that the overall packet size will be bigger than sizeof(buffer),
+which results in memory corruption.
+
+Fix this by only allowing to queue maximum sizeof(buffer) bytes.
+
+This is CVE-2015-3209.
+
+[Fixed 3-space indentation to QEMU's 4-space coding standard.
+--Stefan]
+
+Signed-off-by: Petr Matousek <pmatouse@redhat.com>
+Reported-by: Matt Tait <matttait@google.com>
+Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ hw/net/pcnet.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
+index bdfd38f..68b9981 100644
+--- a/hw/net/pcnet.c
++++ b/hw/net/pcnet.c
+@@ -1241,6 +1241,14 @@ static void pcnet_transmit(PCNetState *s)
+         }
+ 
+         bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
++
++        /* if multi-tmd packet outsizes s->buffer then skip it silently.
++           Note: this is not what real hw does */
++        if (s->xmit_pos + bcnt > sizeof(s->buffer)) {
++            s->xmit_pos = -1;
++            goto txdone;
++        }
++
+         s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
+                          s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));
+         s->xmit_pos += bcnt;
+-- 
+2.2.1
+