From: Yunjian Wang <wangyunj...@huawei.com>
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 <wangyunj...@huawei.com>
---
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
