From: Sasha Levin <levinsasha928@gmail.com>
Date: Mon, 11 Jun 2012 15:18:13 +0000 (-0500)
Subject: 9p: BUG before corrupting memory
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=5fcb08befaf57faa1b00e514915c1660252b8c26;p=openwrt%2Fstaging%2Fblogic.git

9p: BUG before corrupting memory

The BUG_ON() in pack_sg_list() would get triggered only one time after we've
corrupted some memory by sg_set_buf() into an invalid sg buffer.

I'm still working on figuring out why I manage to trigger that bug...

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
---

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 5af18d11b518..2a167658bb95 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -192,10 +192,10 @@ static int pack_sg_list(struct scatterlist *sg, int start,
 		s = rest_of_page(data);
 		if (s > count)
 			s = count;
+		BUG_ON(index > limit);
 		sg_set_buf(&sg[index++], data, s);
 		count -= s;
 		data += s;
-		BUG_ON(index > limit);
 	}
 
 	return index-start;