linux-kernel - Re: [PATCH v4 net] rtnetlink: Fix memory(net

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Date:   Wed, 15 Jul 2020 15:11:56 +0800
From:   Weilong Chen <chenweilong@...wei.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Jiri Pirko" <jiri@...lanox.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "Linux Kernel Network Developers" <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 net] rtnetlink: Fix memory(net_device) leak when
 ->newlink fails

On 2020/7/15 13:45, Cong Wang wrote:
> On Tue, Jul 14, 2020 at 6:27 PM Weilong Chen <chenweilong@...wei.com> wrote:
>>
>> When vlan_newlink call register_vlan_dev fails, it might return error
>> with dev->reg_state = NETREG_UNREGISTERED. The rtnl_newlink should
>> free the memory. But currently rtnl_newlink only free the memory which
>> state is NETREG_UNINITIALIZED.
>>
>> BUG: memory leak
>> unreferenced object 0xffff8881051de000 (size 4096):
>>   comm "syz-executor139", pid 560, jiffies 4294745346 (age 32.445s)
>>   hex dump (first 32 bytes):
>>     76 6c 61 6e 32 00 00 00 00 00 00 00 00 00 00 00  vlan2...........
>>     00 45 28 03 81 88 ff ff 00 00 00 00 00 00 00 00  .E(.............
>>   backtrace:
>>     [<0000000047527e31>] kmalloc_node include/linux/slab.h:578 [inline]
>>     [<0000000047527e31>] kvmalloc_node+0x33/0xd0 mm/util.c:574
>>     [<000000002b59e3bc>] kvmalloc include/linux/mm.h:753 [inline]
>>     [<000000002b59e3bc>] kvzalloc include/linux/mm.h:761 [inline]
>>     [<000000002b59e3bc>] alloc_netdev_mqs+0x83/0xd90 net/core/dev.c:9929
>>     [<000000006076752a>] rtnl_create_link+0x2c0/0xa20 net/core/rtnetlink.c:3067
>>     [<00000000572b3be5>] __rtnl_newlink+0xc9c/0x1330 net/core/rtnetlink.c:3329
>>     [<00000000e84ea553>] rtnl_newlink+0x66/0x90 net/core/rtnetlink.c:3397
>>     [<0000000052c7c0a9>] rtnetlink_rcv_msg+0x540/0x990 net/core/rtnetlink.c:5460
>>     [<000000004b5cb379>] netlink_rcv_skb+0x12b/0x3a0 net/netlink/af_netlink.c:2469
>>     [<00000000c71c20d3>] netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
>>     [<00000000c71c20d3>] netlink_unicast+0x4c6/0x690 net/netlink/af_netlink.c:1329
>>     [<00000000cca72fa9>] netlink_sendmsg+0x735/0xcc0 net/netlink/af_netlink.c:1918
>>     [<000000009221ebf7>] sock_sendmsg_nosec net/socket.c:652 [inline]
>>     [<000000009221ebf7>] sock_sendmsg+0x109/0x140 net/socket.c:672
>>     [<000000001c30ffe4>] ____sys_sendmsg+0x5f5/0x780 net/socket.c:2352
>>     [<00000000b71ca6f3>] ___sys_sendmsg+0x11d/0x1a0 net/socket.c:2406
>>     [<0000000007297384>] __sys_sendmsg+0xeb/0x1b0 net/socket.c:2439
>>     [<000000000eb29b11>] do_syscall_64+0x56/0xa0 arch/x86/entry/common.c:359
>>     [<000000006839b4d0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Fixes: e51fb152318ee6 ("rtnetlink: fix a memory leak when ->newlink fails")
> 
> This bug is apparently not introduced by my commit above.
> 
> It should be commit cb626bf566eb4433318d35681286c494f0,
> right? That commit introduced NETREG_UNREGISTERED on the path.
> 
Yes, you'er right, I'll resubmit.
Thanks.
> .
>