Messages in this thread Patch in this message | | | Subject | [PATCH 3/6] macvtap: zerocopy: validate vector length before pinning user pages | From | Jason Wang <> | Date | Mon, 16 Apr 2012 14:08:07 +0800 |
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Currently we do not validate the vector length before calling get_user_pages_fast(), host stack would be easily overflowed by malicious guest driver who give us a descriptor with length greater than MAX_SKB_FRAGS. Solve this problem by checking the free entries before trying to pin user pages.
Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/net/macvtap.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 7cb2684..d197a78 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -529,6 +529,8 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, } base = (unsigned long)from->iov_base + offset; size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT; + if (i + size >= MAX_SKB_FRAGS) + return -EFAULT; num_pages = get_user_pages_fast(base, size, 0, &page[i]); if ((num_pages != size) || (num_pages > MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags))
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