Blame macvtap-zerocopy-validate-vector-length.patch
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Currently we do not validate the vector length before calling
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get_user_pages_fast(), host stack would be easily overflowed by
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malicious guest driver who give us a descriptor with length greater
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than MAX_SKB_FRAGS. Solve this problem by checking the free entries
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before trying to pin user pages.
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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---
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drivers/net/macvtap.c | 2 ++
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1 files changed, 2 insertions(+), 0 deletions(-)
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diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
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index 7cb2684..d197a78 100644
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--- a/drivers/net/macvtap.c
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+++ b/drivers/net/macvtap.c
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@@ -527,6 +527,8 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
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}
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base = (unsigned long)from->iov_base + offset1;
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size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
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+ if (i + size >= MAX_SKB_FRAGS)
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+ return -EFAULT;
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num_pages = get_user_pages_fast(base, size, 0, &page[i]);
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if ((num_pages != size) ||
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(num_pages > MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags))
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