Re: BUG: net/tipc: NULL-ptr dereference in tipc_nl_publ_dump

[Baozeng Ding <sploving1@gmail.com>]

On 2016/5/15 1:13, Eric Dumazet wrote:
> On Sat, 2016-05-14 at 23:22 +0800, Baozeng Ding wrote:
>> Hello all,
>> The following program triggers NULL-ptr dereference in
>> tipc_nl_publ_dump. The kernel version is 4.6.0-rc7+ (on May 13 commit
>> 1410b74e4061e05a5d2bffb1f99829efce27c8a9). Thanks.
>> ----------------------------------------------------------------------------------
>> netlink: 1 bytes leftover after parsing attributes in process
>> `syz-executor'.
>> kasan: CONFIG_KASAN_INLINE enabled
>> kasan: GPF could be caused by NULL-ptr deref or user memory
>> accessgeneral protection fault: 0000 [#1] SMP KASAN
>> Modules linked in:
>> CPU: 2 PID: 1346 Comm: syz-executor Not tainted 4.6.0-rc7+ #2
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> Ubuntu-1.8.2-1ubuntu1 04/01/2014
>> task: ffff88001eb1dd40 ti: ffff88001bd98000 task.ti: ffff88001bd98000
>> RIP: 0010:[<ffffffff85940bb9>]  [<ffffffff85940bb9>]
>> tipc_nl_publ_dump+0xa39/0xdf0
>> RSP: 0018:ffff88001bd9f428  EFLAGS: 00010246
>> RAX: dffffc0000000000 RBX: ffff88003562efc0 RCX: ffffc900012c7000
>> RDX: 0000000000000000 RSI: ffff880036215d98 RDI: ffff8800196fda98
>> RBP: ffff88001bd9f678 R08: 0000000000000001 R09: 0000000000000000
>> R10: ffffed00032dfb5a R11: 1ffffffff1131255 R12: 0000000000000000
>> R13: ffff88002d0f8040 R14: 0000000000000000 R15: ffff88002ea220a8
>> FS:  00007f0b7c70f700(0000) GS:ffff880036200000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 0000000020b5d7f2 CR3: 00000000301fe000 CR4: 00000000000006e0
>> Stack:
>>    0000000000000000 ffff88002ea22100 ffff88002ea220f8 ffff88002ea220f0
>>    000000001bd9f520 1ffff100037b3e92 ffff88002ea220b0 ffff88001bd9f498
>>    ffffffff815bcc6e ffff880036223e40 ffff88002fd60008 0000000000000000
>> Call Trace:
>>    [<ffffffff84b9d298>] genl_lock_dumpit+0x68/0x90
>> net/netlink/genetlink.c:517
>>    [<ffffffff84b9250a>] netlink_dump+0x36a/0xa40
>> net/netlink/af_netlink.c:2108
>>    [<ffffffff84b95349>] __netlink_dump_start+0x4e9/0x760
>> net/netlink/af_netlink.c:2196
>>    [<ffffffff84b9e5f1>] genl_family_rcv_msg+0xa91/0xc30
>> net/netlink/genetlink.c:584
>>    [<ffffffff84b9e93b>] genl_rcv_msg+0x1ab/0x260 net/netlink/genetlink.c:658
>>    [<ffffffff84b9ca3c>] netlink_rcv_skb+0x29c/0x390
>> net/netlink/af_netlink.c:2277
>>    [<ffffffff84b9db48>] genl_rcv+0x28/0x40 net/netlink/genetlink.c:669
>>    [<     inline     >] netlink_unicast_kernel net/netlink/af_netlink.c:1214
>>    [<ffffffff84b9b352>] netlink_unicast+0x5a2/0x890
>> net/netlink/af_netlink.c:1240
>>    [<ffffffff84b9bfc1>] netlink_sendmsg+0x981/0xcb0
>> net/netlink/af_netlink.c:1786
>>    [<     inline     >] sock_sendmsg_nosec net/socket.c:612
>>    [<ffffffff849ee09a>] sock_sendmsg+0xca/0x110 net/socket.c:622
>>    [<ffffffff849efee8>] ___sys_sendmsg+0x728/0x860 net/socket.c:1946
>>    [<ffffffff849f1ed1>] __sys_sendmsg+0xd1/0x170 net/socket.c:1980
>>    [<     inline     >] SYSC_sendmsg net/socket.c:1991
>>    [<ffffffff849f1f9d>] SyS_sendmsg+0x2d/0x50 net/socket.c:1987
>>    [<ffffffff85b4b340>] entry_SYSCALL_64_fastpath+0x23/0xc1
>> arch/x86/entry/entry_64.S:207
>> Code: df 49 8d 7e 10 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 df 01 00 00
>> 4d 8b 76 10 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6
>> 14 02 4c 89 f0 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85
>> RIP  [<ffffffff85940bb9>] tipc_nl_publ_dump+0xa39/0xdf0
>> net/tipc/socket.c:2810
>>    RSP <ffff88001bd9f428>
>> ---[ end trace e8355fded2057a4f ]---
> Probable fix :
>
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index 3eeb50a27b89..5f80d3fa9c85 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -2807,6 +2807,9 @@ int tipc_nl_publ_dump(struct sk_buff *skb, struct netlink_callback *cb)
>   		if (err)
>   			return err;
>   
> +		if (!attrs[TIPC_NLA_SOCK])
> +			return -EINVAL;
> +
>   		err = nla_parse_nested(sock, TIPC_NLA_SOCK_MAX,
>   				       attrs[TIPC_NLA_SOCK],
>   				       tipc_nl_sock_policy);
>
Yes. I tested with the patch. It works. Thanks.