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]> --- This patch is needed for stable. --- drivers/net/tun.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 7eab5fc..01d5a86 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1109,7 +1109,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } else copylen = len; - skb = tun_alloc_skb(tfile, align, copylen, gso.hdr_len, noblock); + skb = tun_alloc_skb(tfile, align, copylen, + zerocopy ? copylen : gso.hdr_len, 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/
