54 lines
2.0 KiB
Diff
54 lines
2.0 KiB
Diff
From: Jason Wang <jasowang@redhat.com>
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Date: Wed, 10 Jul 2013 13:43:27 +0800
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Subject: tuntap: correctly linearize skb when zerocopy is used
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Origin: https://git.kernel.org/linus/3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d
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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 tun_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 0690899b4d4501b3505be069b9a687e68ccbe15b
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(tun: experimental zero copy tx support)
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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/tun.c | 9 ++++++---
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1 file changed, 6 insertions(+), 3 deletions(-)
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diff --git a/drivers/net/tun.c b/drivers/net/tun.c
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index 7eab5fc..5cdcf92 100644
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--- a/drivers/net/tun.c
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+++ b/drivers/net/tun.c
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@@ -1042,7 +1042,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
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{
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struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
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struct sk_buff *skb;
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- size_t len = total_len, align = NET_SKB_PAD;
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+ size_t len = total_len, align = NET_SKB_PAD, linear;
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struct virtio_net_hdr gso = { 0 };
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int offset = 0;
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int copylen;
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@@ -1106,10 +1106,13 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
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copylen = gso.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 = gso.hdr_len;
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+ }
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- skb = tun_alloc_skb(tfile, align, copylen, gso.hdr_len, noblock);
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+ skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
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if (IS_ERR(skb)) {
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if (PTR_ERR(skb) != -EAGAIN)
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tun->dev->stats.rx_dropped++;
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