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authorJason Wang <jasowang@redhat.com>2013-07-10 09:43:27 +0400
committerDavid S. Miller <davem@davemloft.net>2013-07-11 05:45:52 +0400
commit3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d (patch)
treefe4138595758de2c756740239bf214a819b490d4 /drivers/net/tun.c
parent440d57bc5ff55ec1efb3efc9cbe9420b4bbdfefa (diff)
downloadlinux-3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d.tar.xz
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.c9
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++;