On Wed, Jul 10, 2013 at 01:43:27PM +0800, Jason Wang wrote: > 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 <[email protected]> > Signed-off-by: Jason Wang <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]> > --- > - This patch is needed for stable. > - Changes from v1: introduce a local variable to track linear size > --- > 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 9c61f87..c3cb60b 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1044,7 +1044,7 @@ 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; > @@ -1108,10 +1108,13 @@ 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++; > -- > 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
