[Qemu-devel] [PATCH] block/iscsi: fix segfault if writesame fails

[Peter Lieven <pl@kamp.de>]

commit fa6252b0 introduced a segfault because it tries
to read iTask.task->sense after iTask.task has been
freed.

CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/block/iscsi.c b/block/iscsi.c
index f8e496f..123fa06 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -830,6 +830,15 @@ retry:
         qemu_coroutine_yield();
     }
 
+    if (iTask.status == SCSI_STATUS_CHECK_CONDITION &&
+        iTask.task->sense.key == SCSI_SENSE_ILLEGAL_REQUEST &&
+        iTask.task->sense.ascq == SCSI_SENSE_ASCQ_INVALID_OPERATION_CODE) {
+        /* WRITE SAME is not supported by the target */
+        iscsilun->has_write_same = false;
+        scsi_free_scsi_task(iTask.task);
+        return -ENOTSUP;
+    }
+
     if (iTask.task != NULL) {
         scsi_free_scsi_task(iTask.task);
         iTask.task = NULL;
@@ -840,14 +849,6 @@ retry:
     }
 
     if (iTask.status != SCSI_STATUS_GOOD) {
-        if (iTask.status == SCSI_STATUS_CHECK_CONDITION &&
-            iTask.task->sense.key == SCSI_SENSE_ILLEGAL_REQUEST &&
-            iTask.task->sense.ascq == SCSI_SENSE_ASCQ_INVALID_OPERATION_CODE) {
-            /* WRITE SAME is not supported by the target */
-            iscsilun->has_write_same = false;
-            return -ENOTSUP;
-        }
-
         return -EIO;
     }
 
-- 
1.7.9.5