54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From: Jason Wang <jasowang@redhat.com>
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Date: Wed, 10 Jul 2013 13:43:28 +0800
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Subject: macvtap: correctly linearize skb when zerocopy is used
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Origin: https://git.kernel.org/linus/61d46bf979d5cd7c164709a80ad5676a35494aae
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Userspace may produce vectors greater than MAX_SKB_FRAGS. When we try to
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linearize parts of the skb to let the rest of iov to be fit in
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the frags, we need count copylen into linear when calling macvtap_alloc_skb()
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instead of partly counting it into data_len. Since this breaks
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zerocopy_sg_from_iovec() since its inner counter assumes nr_frags should
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be zero at beginning. This cause nr_frags to be increased wrongly without
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setting the correct frags.
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This bug were introduced from b92946e2919134ebe2a4083e4302236295ea2a73
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(macvtap: zerocopy: validate vectors before building skb).
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Cc: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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Acked-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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drivers/net/macvtap.c | 8 ++++++--
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1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
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index f2c4a3b..876c722 100644
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--- a/drivers/net/macvtap.c
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+++ b/drivers/net/macvtap.c
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@@ -712,6 +712,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
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int vnet_hdr_len = 0;
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int copylen = 0;
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bool zerocopy = false;
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+ size_t linear;
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if (q->flags & IFF_VNET_HDR) {
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vnet_hdr_len = q->vnet_hdr_sz;
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@@ -766,11 +767,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
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copylen = vnet_hdr.hdr_len;
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if (!copylen)
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copylen = GOODCOPY_LEN;
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- } else
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+ linear = copylen;
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+ } else {
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copylen = len;
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+ linear = vnet_hdr.hdr_len;
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+ }
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skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen,
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- vnet_hdr.hdr_len, noblock, &err);
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+ linear, noblock, &err);
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if (!skb)
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goto err;
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