1 files changed, 43 insertions, 0 deletions
diff --git a/main/xen/xsa71.patch b/main/xen/xsa71.patch
new file mode 100644
index 0000000000..45e52eb0f8
--- /dev/null
+++ b/main/xen/xsa71.patch
@@ -0,0 +1,43 @@
+From 23260e589e52ec83349f22198eab2331b5a1684e Mon Sep 17 00:00:00 2001
+From: Matthew Daley <mattjd@gmail.com>
+Date: Wed, 25 Sep 2013 12:28:47 +1200
+Subject: [PATCH] xen_disk: mark ioreq as mapped before unmapping in error
+ case
+
+Commit c6961b7d ("xen_disk: use bdrv_aio_flush instead of bdrv_flush")
+modified the semantics of ioreq_{un,}map so that they are idempotent if
+called when they're not needed (ie., twice in a row). However, it neglected
+to handle the case where batch mapping is not being used (the default), and
+one of the grants fails to map. In this case, ioreq_unmap will be called to
+unwind and unmap any mappings already performed, but ioreq_unmap simply
+returns due to the aforementioned change (the ioreq has not already been
+marked as mapped).
+
+The frontend user can therefore force xen_disk to leak grant mappings, a
+per-backend-domain limited resource.
+
+Fix by marking the ioreq as mapped before calling ioreq_unmap in this
+situation.
+
+This is XSA-71 / CVE-2013-4375
+
+Signed-off-by: Matthew Daley <mattjd@gmail.com>
+---
+ hw/xen_disk.c |    1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/tools/qemu-xen/hw/xen_disk.c b/tools/qemu-xen/hw/xen_disk.c
+index a402ac8..1cdfcbc 100644
+--- a/tools/qemu-xen/hw/xen_disk.c
++++ b/tools/qemu-xen/hw/xen_disk.c
+@@ -299,6 +299,7 @@ static int ioreq_map(struct ioreq *ioreq)
+                 xen_be_printf(&ioreq->blkdev->xendev, 0,
+                               "can't map grant ref %d (%s, %d maps)\n",
+                               refs[i], strerror(errno), ioreq->blkdev->cnt_map);
++                ioreq->mapped = 1;
+                 ioreq_unmap(ioreq);
+                 return -1;
+             }
+-- 
+1.7.10.4
+