From: Michael S. Tsirkin <mst@redhat.com>
Date: Tue, 14 Sep 2010 13:15:52 +0000 (+0200)
Subject: vhost-net: fix range checking in mrg bufs case
X-Git-Tag: v2.6.36-rc6~6^2~42^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ee05d6939ed17b55e9c2466af32c208e0d547eb8;p=pandora-kernel.git

vhost-net: fix range checking in mrg bufs case

In mergeable buffer case, we use headcount, log_num
and seg as indexes in same-size arrays, and
we know that headcount <= seg and
log_num equals either 0 or seg.

Therefore, the right thing to do is range-check seg,
not headcount as we do now: these will be different
if guest chains s/g descriptors (this does not
happen now, but we can not trust the guest).

Long term, we should add BUG_ON checks to verify
two other indexes are what we think they should be.

Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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