[PATCH net-next] tun: fix ubuf refcount incorrectly on error path
From: wangyunjian <hidden>
Date: 2020-12-03 08:02:51
Subsystem:
networking drivers, the rest, tun/tap driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Willem de Bruijn, Jason Wang
From: Yunjian Wang <redacted>
After setting callback for ubuf_info of skb, the callback
(vhost_net_zerocopy_callback) will be called to decrease
the refcount when freeing skb. But when an exception occurs
afterwards, the error handling in vhost handle_tx() will
try to decrease the same refcount again. This is wrong and
fix this by clearing ubuf_info when meeting errors.
Fixes: 4477138fa0ae ("tun: properly test for IFF_UP")
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Yunjian Wang <redacted>
---
drivers/net/tun.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2dc1988a8973..3614bb1b6d35 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c@@ -1861,6 +1861,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (unlikely(!(tun->dev->flags & IFF_UP))) { err = -EIO; rcu_read_unlock(); + if (zerocopy) { + skb_shinfo(skb)->destructor_arg = NULL; + skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY; + skb_shinfo(skb)->tx_flags &= ~SKBTX_SHARED_FRAG; + } + goto drop; }
@@ -1874,6 +1880,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (unlikely(headlen > skb_headlen(skb))) { atomic_long_inc(&tun->dev->rx_dropped); + if (zerocopy) { + skb_shinfo(skb)->destructor_arg = NULL; + skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY; + skb_shinfo(skb)->tx_flags &= ~SKBTX_SHARED_FRAG; + } napi_free_frags(&tfile->napi); rcu_read_unlock(); mutex_unlock(&tfile->napi_mutex);
--
2.18.1