From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 25 Nov 2011 11:06:22 +0000 (+0100)
Subject: qiov: prevent double free or use-after-free
X-Git-Tag: qemu-xen-4.2.0~47
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=6061f16a8a119a46e61f2ddbabdb58f83e8857f7;p=qemu-upstream-4.2-testing.git

qiov: prevent double free or use-after-free

qemu_iovec_destroy does not clear the QEMUIOVector fully, and the data
could thus be used after free or freed again.  While I do not know any
example in the tree, I observed this using virtio-scsi (and SCSI
scatter/gather) when canceling DMA requests.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---

diff --git a/cutils.c b/cutils.c
index 6db6304bb..24b3fe355 100644
--- a/cutils.c
+++ b/cutils.c
@@ -217,7 +217,10 @@ void qemu_iovec_destroy(QEMUIOVector *qiov)
 {
     assert(qiov->nalloc != -1);
 
+    qemu_iovec_reset(qiov);
     g_free(qiov->iov);
+    qiov->nalloc = 0;
+    qiov->iov = NULL;
 }
 
 void qemu_iovec_reset(QEMUIOVector *qiov)