On Thu, 26 Nov 2020 21:23:12 +0800
Yang Yingliang <yangyingli...@huawei.com> wrote:
> I got a memleak report when doing fault-inject test:
>
> unreferenced object 0xffff88810ace9000 (size 1024):
> comm "ip", pid 4622, jiffies 4295457037 (age 43.378s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<00000000008abe41>] __kmalloc+0x10f/0x210
> [<000000005d3533a6>] veth_dev_init+0x140/0x310
> [<0000000088353c64>] register_netdevice+0x496/0x7a0
> [<000000001324d322>] veth_newlink+0x40b/0x960
> [<00000000d0799866>] __rtnl_newlink+0xd8c/0x1360
> [<00000000d616040a>] rtnl_newlink+0x6b/0xa0
> [<00000000e0a1600d>] rtnetlink_rcv_msg+0x3cc/0x9e0
> [<000000009eeff98b>] netlink_rcv_skb+0x130/0x3a0
> [<00000000500f8be1>] netlink_unicast+0x4da/0x700
> [<00000000666c03b3>] netlink_sendmsg+0x7fe/0xcb0
> [<0000000073b28103>] sock_sendmsg+0x143/0x180
> [<00000000ad746a30>] ____sys_sendmsg+0x677/0x810
> [<0000000087dd98e5>] ___sys_sendmsg+0x105/0x180
> [<00000000028dd365>] __sys_sendmsg+0xf0/0x1c0
> [<00000000a6bfbae6>] do_syscall_64+0x33/0x40
> [<00000000e00521b4>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> It seems ifb and loopback may also hit the leak, so I try to fix this in
> register_netdevice().
>
> In common case, priv_destructor() will be called in netdev_run_todo()
> after calling ndo_uninit() in rollback_registered(), on other error
> path in register_netdevice(), ndo_uninit() and priv_destructor() are
> called before register_netdevice() return, but in this case,
> priv_destructor() will never be called, then it causes memory leak,
> so we should call priv_destructor() here.
>
> Reported-by: Hulk Robot <hul...@huawei.com>
> Signed-off-by: Yang Yingliang <yangyingli...@huawei.com>
> ---
> net/core/dev.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 82dc6b48e45f..907204395b64 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -10000,6 +10000,17 @@ int register_netdevice(struct net_device *dev)
> ret = notifier_to_errno(ret);
> if (ret) {
> rollback_registered(dev);
> + /*
> + * In common case, priv_destructor() will be
> + * called in netdev_run_todo() after calling
> + * ndo_uninit() in rollback_registered().
> + * But in this case, priv_destructor() will
> + * never be called, then it causes memory
> + * leak, so we should call priv_destructor()
> + * here.
> + */
> + if (dev->priv_destructor)
> + dev->priv_destructor(dev);
Are you sure this is safe?
Several devices have destructors that call free_netdev.
Up until now a common pattern for those devices was to call
free_netdev on error. After this change it would lead to double free.
