linux-kernel - Re: [RFC PATCH] netlink: Safer deletion of sk_bind

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <54058376.9090700@mentor.com>
Date:	Tue, 2 Sep 2014 14:14:38 +0530
From:	Harish Jenny Kandiga Nagaraj <harish_kandiga@...tor.com>
To:	David Miller <davem@...emloft.net>
CC:	<dborkman@...hat.com>, <tgraf@...g.ch>, <ebiederm@...ssion.com>,
	<darkjames-ws@...kjames.pl>, <rgb@...hat.com>,
	<eric.dumazet@...il.com>, <stephen@...workplumber.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] netlink: Safer deletion of sk_bind_node

In one of our random test runs we observed the crash mentioned in the previous mail.

After debugging we found out that the call flow of the inline and static functions were
netlink_release
-----netlink_remove
---------__sk_del_bind_node
--------------__hlist_del

*pprev was NULL in __hlist_del function while deleting &sk->sk_bind_node hlist_node. Hence the patch was given.

In netlink_remove function , first the sk_del_node_init function will be called. This internally calls __sk_del_node_init function. While deleting &sk->sk_node hlist_node using __sk_del_node function there is a NULL check with sk_hashed function.

Why there is no NULL check for *pprev while deleting &sk->sk_bind_node ?

On Tuesday 02 September 2014 10:33 AM, David Miller wrote:
> From: Harish Jenny K N
> Date: Mon, 1 Sep 2014 12:38:29 +0530
>
> Firstly, you really need to fix your outgoing email so that your email
> address appears in your From: header properly.
>
>> From: Harish Jenny K N <harish_kandiga@...tor.com>
>>
>>     Unable to handle kernel NULL pointer dereference at virtual address 00000000
>>         (netlink_release+0x0/0x2a0) from [<8034e78c>] (sock_release+0x28/0xa4)
>>         (sock_release+0x0/0xa4) from [<8034e830>] (sock_close+0x28/0x34)
>>         (sock_close+0x0/0x34) from [<800f3490>] (__fput+0xf0/0x1ec)
>>         (__fput+0x0/0x1ec) from [<800f3634>] (____fput+0x10/0x14)
>>         (____fput+0x0/0x14) from [<80040a64>] (task_work_run+0xb8/0xd8)
>>         (task_work_run+0x0/0xd8) from [<800113a0>] (do_work_pending+0xb0/0xc4)
>>         (do_work_pending+0x0/0xc4) from [<8000d960>] (work_pending+0xc/0x20)
>>     Call flow of the inline and static functions
>>         netlink_release
>>         -----netlink_remove
>>         ---------__sk_del_bind_node
>>         --------------__hlist_del
>>
>> Signed-off-by: Harish Jenny K N <harish_kandiga@...tor.com>
> This doesn't tell us anything about how this situation can be
> arrived at.
>
> When subscriptions changes, we delete the node with the table lock
> held if subscriptions goes to zero.  We only try to delete the node
> when subscriptions was zero.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/