3.6.11.9-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang [ Upstream commit 3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d ] 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 Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Steven Rostedt --- drivers/net/tun.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index ef7710f..ad08dee 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -692,7 +692,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, void *msg_control, { 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; @@ -755,10 +755,14 @@ static ssize_t tun_get_user(struct tun_struct *tun, void *msg_control, copylen = gso.hdr_len; if (!copylen) copylen = GOODCOPY_LEN; - } else + linear = copylen; + } else { copylen = len; + linear = gso.hdr_len; + } skb = tun_alloc_skb(tun, align, copylen, gso.hdr_len, noblock); + skb = tun_alloc_skb(tun, align, copylen, linear, noblock); if (IS_ERR(skb)) { if (PTR_ERR(skb) != -EAGAIN) tun->dev->stats.rx_dropped++; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/