[Qemu-devel] [PATCH] Ensure an error is reported to user if 9pfs mount tag is too long

["Daniel P. Berrange" <berrange@redhat.com>]

From: "Daniel P. Berrange" <berrange@redhat.com>

If the 9pfs mount tag is longer than MAX_TAG_LEN bytes, rather than
silently truncating the tag which will likely break the guest OS,
report an immediate error and exit QEMU

* hw/9pfs/virtio-9p-device.c: Report error & exit if mount tag is
  too long

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 hw/9pfs/virtio-9p-device.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index 97f2da5..8ca38d3 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -117,7 +117,9 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
     s->ctx.fs_root = g_strdup(fse->path);
     len = strlen(conf->tag);
     if (len > MAX_TAG_LEN) {
-        len = MAX_TAG_LEN;
+	fprintf(stderr, "mount tag '%s' (%d bytes) is longer than maximum (%d bytes)",
+		conf->tag, len, MAX_TAG_LEN);
+	exit(1);
     }
     /* s->tag is non-NULL terminated string */
     s->tag = g_malloc(len);
-- 
1.7.6.2