[Qemu-devel] [PATCH 1.0] qiov: prevent double free or use-after-free

[Paolo Bonzini]

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 <address@hidden>
---
 cutils.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/cutils.c b/cutils.c
index 5d995bc..731a27e 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)
-- 
1.7.7.1