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| author | Jason Wang <jasowang@redhat.com> | 2013-07-10 13:43:27 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-07-10 18:45:52 -0700 |
| commit | 3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d (patch) | |
| tree | fe4138595758de2c756740239bf214a819b490d4 /drivers/net/tun.c | |
| parent | 440d57bc5ff55ec1efb3efc9cbe9420b4bbdfefa (diff) | |
| download | lwn-3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d.tar.gz lwn-3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d.zip | |
tuntap: correctly linearize skb when zerocopy is used
Userspace may produce vectors greater than MAX_SKB_FRAGS. When we try to
linearize parts of the skb to let the rest of iov to be fit in
the frags, we need count copylen into linear when calling tun_alloc_skb()
instead of partly counting it into data_len. Since this breaks
zerocopy_sg_from_iovec() since its inner counter assumes nr_frags should
be zero at beginning. This cause nr_frags to be increased wrongly without
setting the correct frags.
This bug were introduced from 0690899b4d4501b3505be069b9a687e68ccbe15b
(tun: experimental zero copy tx support)
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
| -rw-r--r-- | drivers/net/tun.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 7eab5fcd064f..5cdcf92eb310 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1042,7 +1042,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, { struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) }; struct sk_buff *skb; - size_t len = total_len, align = NET_SKB_PAD; + size_t len = total_len, align = NET_SKB_PAD, linear; struct virtio_net_hdr gso = { 0 }; int offset = 0; int copylen; @@ -1106,10 +1106,13 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, copylen = gso.hdr_len; if (!copylen) copylen = GOODCOPY_LEN; - } else + linear = copylen; + } else { copylen = len; + linear = gso.hdr_len; + } - skb = tun_alloc_skb(tfile, align, copylen, gso.hdr_len, noblock); + skb = tun_alloc_skb(tfile, align, copylen, linear, noblock); if (IS_ERR(skb)) { if (PTR_ERR(skb) != -EAGAIN) tun->dev->stats.rx_dropped++; |