From ca525ebda9b0869bddd602c7ac2884ef5cf96507 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 10 Jan 2013 15:08:05 +0100
Subject: [PATCH] scsi: fix segfault with 0-byte disk

When a 0-sized disk is found, READ CAPACITY will return a
LUN NOT READY error.  However, because it returns -1 instead
of zero, the HBA will call scsi_req_continue.  This will
typically cause a segmentation fault or an assertion failure.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi-disk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 7ed1bde..fbca538 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -1683,7 +1683,7 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
         bdrv_get_geometry(s->qdev.conf.bs, &nb_sectors);
         if (!nb_sectors) {
             scsi_check_condition(r, SENSE_CODE(LUN_NOT_READY));
-            return -1;
+            return 0;
         }
         if ((req->cmd.buf[8] & 1) == 0 && req->cmd.lba) {
             goto illegal_request;
@@ -1750,7 +1750,7 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
             bdrv_get_geometry(s->qdev.conf.bs, &nb_sectors);
             if (!nb_sectors) {
                 scsi_check_condition(r, SENSE_CODE(LUN_NOT_READY));
-                return -1;
+                return 0;
             }
             if ((req->cmd.buf[14] & 1) == 0 && req->cmd.lba) {
                 goto illegal_request;