lkml.org 
[lkml]   [2011]   [May]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 2/3] virtio_ring: check used_event offset
Nothing's wrong with vring_size as is, but it's nice
to check that the new field in the avail ring
won't overlow into the used ring.

Reported-by: Tom Lendacky <tahm@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/virtio_ring.h | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 2a3b0ea..089cbf2 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -119,7 +119,13 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p,

static inline unsigned vring_size(unsigned int num, unsigned long align)
{
- return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
+#ifdef __KERNEL__
+ /* Older versions did not have used_event field at the end of the
+ * avail ring. Used ring offset must be compatible with such devices. */
+ size_t s = sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num);
+ BUG_ON(ALIGN(s, align) != ALIGN(s + sizeof(__u16), align));
+#endif
+ return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)
+ align - 1) & ~(align - 1))
+ sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
}
--
1.7.5.53.gc233e


\
 
 \ /
  Last update: 2011-05-05 17:13    [from the cache]
©2003-2011 Jasper Spaans