[Qemu-devel] [PULL 1/4] usb-mtp: return incomplete transfer on a lstat failure

[Gerd Hoffmann <kraxel@redhat.com>]

From: Bandan Das <bsd@redhat.com>

MTP writes objects in small chunks and at the end gets the
real file size to update the object metadata. If this fails for
any reason, return an INCOMPLETE_TRANSFER to the initiator

Spotted by Coverity: CID 1398651

Signed-off-by: Bandan Das <bsd@redhat.com>
Message-id: 20190306210409.14842-2-bsd@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/dev-mtp.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
index 4ee4fc5a893a..4dde14fc7887 100644
--- a/hw/usb/dev-mtp.c
+++ b/hw/usb/dev-mtp.c
@@ -1591,14 +1591,18 @@ done:
         return ret;
 }
 
-static void usb_mtp_update_object(MTPObject *parent, char *name)
+static int usb_mtp_update_object(MTPObject *parent, char *name)
 {
+    int ret = -1;
+
     MTPObject *o =
         usb_mtp_object_lookup_name(parent, name, strlen(name));
 
     if (o) {
-        lstat(o->path, &o->stat);
+        ret = lstat(o->path, &o->stat);
     }
+
+    return ret;
 }
 
 static void usb_mtp_write_data(MTPState *s)
@@ -1655,13 +1659,18 @@ static void usb_mtp_write_data(MTPState *s)
         if (d->write_status != WRITE_END) {
             return;
         } else {
-            /* Only for < 4G file sizes */
-            if (s->dataset.size != 0xFFFFFFFF && d->offset != s->dataset.size) {
+            /*
+             * Return an incomplete transfer if file size doesn't match
+             * for < 4G file or if lstat fails which will result in an incorrect
+             * file size
+             */
+            if ((s->dataset.size != 0xFFFFFFFF &&
+                 d->offset != s->dataset.size) ||
+                usb_mtp_update_object(parent, s->dataset.filename)) {
                 usb_mtp_queue_result(s, RES_INCOMPLETE_TRANSFER, d->trans,
                                      0, 0, 0, 0);
                 goto done;
             }
-            usb_mtp_update_object(parent, s->dataset.filename);
         }
     }
 
-- 
2.18.1