Recently introduced FUA support also gave us a use-after-free
of the BlockAcctCookie within a SCSIDiskReq, due to unbalanced
reference counting.
The patch fixes this by making scsi_do_read look like a combination
of scsi_*_complete + scsi_*_data. It does both a ref (like
scsi_read_data) and an unref (like scsi_flush_complete).
Reported-by: David Gibson <da...@gibson.dropbear.id.au>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/scsi-disk.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index a029ab6..eca00a6 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -296,6 +296,13 @@ static void scsi_do_read(void *opaque, int ret)
}
}
+ if (r->req.io_canceled) {
+ return;
+ }
+
+ /* The request is used as the AIO opaque value, so add a ref. */
+ scsi_req_ref(&r->req);
+
if (r->req.sg) {
dma_acct_start(s->qdev.conf.bs, &r->acct, r->req.sg, BDRV_ACCT_READ);
r->req.resid -= r->req.sg->size;
--
1.7.9.3
