From: Yang Yingliang <yangyingliang@huawei.com>
To: Paul Moore <paul@paul-moore.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
Oleg Nesterov <oleg@redhat.com>, <john.johansen@canonical.com>,
"chengjian (D)" <cj.chengjian@huawei.com>,
Kees Cook <keescook@chromium.org>, NeilBrown <neilb@suse.com>,
Anna Schumaker <Anna.Schumaker@netapp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
"Xiexiuqi (Xie XiuQi)" <xiexiuqi@huawei.com>,
Li Bin <huawei.libin@huawei.com>,
"Jason Yan" <yanaijie@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Linux Security Module list
<linux-security-module@vger.kernel.org>,
SELinux <selinux@vger.kernel.org>
Subject: Re: kernel BUG at kernel/cred.c:434!
Date: Fri, 19 Apr 2019 10:34:44 +0800 [thread overview]
Message-ID: <5CB933C4.7000300@huawei.com> (raw)
In-Reply-To: <CAHC9VhQkrR+m9_dYLg4VG-26TdUnf8XFjbmuVQ70YCOp6DhN_g@mail.gmail.com>
On 2019/4/19 10:04, Paul Moore wrote:
> On Wed, Apr 17, 2019 at 10:50 PM Yang Yingliang
> <yangyingliang@huawei.com> wrote:
>> On 2019/4/18 8:24, Casey Schaufler wrote:
>>> On 4/17/2019 4:39 PM, Paul Moore wrote:
>>>> Since it looks like all three LSMs which implement the setprocattr
>>>> hook are vulnerable I'm open to the idea that proc_pid_attr_write() is
>>>> a better choice for the cred != read_cred check, but I would want to
>>>> make sure John and Casey are okay with that.
>>>>
>>>> John?
>>>>
>>>> Casey?
>>> I'm fine with the change going into proc_pid_attr_write().
>> The cred != real_cred checking is not enough.
>>
>> Consider this situation, when doing override, cred, real_cred and
>> new_cred are all same:
>>
>> after override_creds() cred == real_cred == new1_cred
> I'm sorry, you've lost me. After override_creds() returns
> current->cred and current->real_cred are not going to be the same,
> yes?
It's possible the new cred is equal to current->real_cred and
current->cred,
so after overrides_creds(), they have the same value.
>
>> after prepare_creds() new2_cred
>> after commit_creds() becasue the check is false, so cred ==
>> real_cred == new2_cred
>> after revert_creds() cred == new1_cred, real_cred == new2_cred
>>
>> It will cause cred != real_cred finally.
next prev parent reply other threads:[~2019-04-19 2:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6e4428ca-3da1-a033-08f7-a51e57503989@huawei.com>
2019-04-12 15:28 ` kernel BUG at kernel/cred.c:434! Casey Schaufler
2019-04-15 13:43 ` Oleg Nesterov
2019-04-15 14:48 ` Paul Moore
2019-04-15 15:05 ` Oleg Nesterov
2019-04-15 16:20 ` Paul Moore
2019-04-16 3:40 ` Kees Cook
2019-04-16 14:46 ` chengjian (D)
2019-04-17 14:30 ` Paul Moore
2019-04-17 14:57 ` Oleg Nesterov
2019-04-17 15:39 ` Casey Schaufler
2019-04-17 15:40 ` Paul Moore
2019-04-17 16:27 ` Oleg Nesterov
2019-04-17 16:42 ` Casey Schaufler
2019-04-18 13:39 ` Stephen Smalley
2019-04-17 23:39 ` Paul Moore
2019-04-18 0:17 ` John Johansen
2019-04-18 0:24 ` Casey Schaufler
2019-04-18 2:49 ` Yang Yingliang
2019-04-19 2:04 ` Paul Moore
2019-04-19 2:34 ` Yang Yingliang [this message]
2019-04-19 13:24 ` Paul Moore
2019-04-19 14:34 ` Yang Yingliang
2019-04-19 16:13 ` Paul Moore
2019-04-20 7:38 ` Yang Yingliang
2019-04-22 19:48 ` Paul Moore
2019-04-23 4:08 ` Yang Yingliang
2019-04-23 20:18 ` Paul Moore
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