Re: [PATCH v2 1/3] tipc: fix memory leak issue

[Eric Dumazet <eric.dumazet@gmail.com>]

On 8/12/19 9:32 AM, Ying Xue wrote:
> syzbot found the following memory leak:
> 
> [   68.602482][ T7130] kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> BUG: memory leak
> unreferenced object 0xffff88810df83c00 (size 512):
>   comm "softirq", pid 0, jiffies 4294942354 (age 19.830s)
>   hex dump (first 32 bytes):
>     38 1a 0d 0f 81 88 ff ff 38 1a 0d 0f 81 88 ff ff  8.......8.......
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<000000009375ee42>] kmem_cache_alloc_node+0x153/0x2a0
>     [<000000004c563922>] __alloc_skb+0x6e/0x210
>     [<00000000ec87bfa1>] tipc_buf_acquire+0x2f/0x80
>     [<00000000d151ef84>] tipc_msg_create+0x37/0xe0
>     [<000000008bb437b0>] tipc_group_create_event+0xb3/0x1b0
>     [<00000000947b1d0f>] tipc_group_proto_rcv+0x569/0x640
>     [<00000000b75ab039>] tipc_sk_filter_rcv+0x9ac/0xf20
>     [<000000000dab7a6c>] tipc_sk_rcv+0x494/0x8a0
>     [<00000000023a7ddd>] tipc_node_xmit+0x196/0x1f0
>     [<00000000337dd9eb>] tipc_node_distr_xmit+0x7d/0x120
>     [<00000000b6375182>] tipc_group_delete+0xe6/0x130
>     [<000000000361ba2b>] tipc_sk_leave+0x57/0xb0
>     [<000000009df90505>] tipc_release+0x7b/0x5e0
>     [<000000009f3189da>] __sock_release+0x4b/0xe0
>     [<00000000d3568ee0>] sock_close+0x1b/0x30
>     [<00000000266a6215>] __fput+0xed/0x300
> 
> Reported-by: syzbot+78fbe679c8ca8d264a8d@syzkaller.appspotmail.com
> Signed-off-by: Hillf Danton <hdanton@sina.com>
> Signed-off-by: Ying Xue <ying.xue@windriver.com>
> ---
>  net/tipc/node.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/net/tipc/node.c b/net/tipc/node.c
> index 7ca0190..d1852fc 100644
> --- a/net/tipc/node.c
> +++ b/net/tipc/node.c
> @@ -1469,10 +1469,13 @@ int tipc_node_xmit(struct net *net, struct sk_buff_head *list,
>  	spin_unlock_bh(&le->lock);
>  	tipc_node_read_unlock(n);
>  
> -	if (unlikely(rc == -ENOBUFS))
> +	if (unlikely(rc == -ENOBUFS)) {
>  		tipc_node_link_down(n, bearer_id, false);
> -	else
> +		skb_queue_purge(list);
> +		skb_queue_purge(&xmitq);

This will crash if you enable LOCKDEP

> +	} else {
>  		tipc_bearer_xmit(net, bearer_id, &xmitq, &le->maddr);
> +	}
>  
>  	tipc_node_put(n);
>  
>