[PATCH net v2] tun: fix ubuf refcount incorrectly on error path
From: wangyunjian <hidden>
Date: 2020-12-09 12:42:56
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 delay copying ubuf_info until we're sure
there's no 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>
---
v2:
Updated code, fix by delay copying ubuf_info
---
drivers/net/tun.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2dc1988a8973..2ea822328e73 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c@@ -1637,6 +1637,20 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, return NULL; } +/* copy ubuf_info for callback when skb has no error */ +static inline void tun_copy_ubuf_info(struct sk_buff *skb, bool zerocopy, void *msg_control) +{ + if (zerocopy) { + skb_shinfo(skb)->destructor_arg = msg_control; + skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; + skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; + } else if (msg_control) { + struct ubuf_info *uarg = msg_control; + + uarg->callback(uarg, false); + } +} + /* Get packet from user space buffer */ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, void *msg_control, struct iov_iter *from,
@@ -1812,16 +1826,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, break; } - /* copy skb_ubuf_info for callback when skb has no error */ - if (zerocopy) { - skb_shinfo(skb)->destructor_arg = msg_control; - skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; - skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; - } else if (msg_control) { - struct ubuf_info *uarg = msg_control; - uarg->callback(uarg, false); - } - skb_reset_network_header(skb); skb_probe_transport_header(skb); skb_record_rx_queue(skb, tfile->queue_index);
@@ -1830,6 +1834,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, struct bpf_prog *xdp_prog; int ret; + tun_copy_ubuf_info(skb, zerocopy, msg_control); local_bh_disable(); rcu_read_lock(); xdp_prog = rcu_dereference(tun->xdp_prog);
@@ -1881,6 +1886,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, return -ENOMEM; } + tun_copy_ubuf_info(skb, zerocopy, msg_control); local_bh_disable(); napi_gro_frags(&tfile->napi); local_bh_enable();
@@ -1889,6 +1895,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, struct sk_buff_head *queue = &tfile->sk.sk_write_queue; int queue_len; + tun_copy_ubuf_info(skb, zerocopy, msg_control); spin_lock_bh(&queue->lock); __skb_queue_tail(queue, skb); queue_len = skb_queue_len(queue);
@@ -1899,8 +1906,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, local_bh_enable(); } else if (!IS_ENABLED(CONFIG_4KSTACKS)) { + tun_copy_ubuf_info(skb, zerocopy, msg_control); tun_rx_batched(tun, tfile, skb, more); } else { + tun_copy_ubuf_info(skb, zerocopy, msg_control); netif_rx_ni(skb); } rcu_read_unlock();
--
2.23.0