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Date:   Wed, 17 Apr 2019 16:57:11 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Paul Moore <paul@paul-moore.com>
Cc:     "chengjian (D)" <cj.chengjian@huawei.com>,
        Kees Cook <keescook@chromium.org>,
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        Linux Security Module list 
        <linux-security-module@vger.kernel.org>,
        SELinux <selinux@vger.kernel.org>,
        Yang Yingliang <yangyingliang@huawei.com>
Subject: Re: kernel BUG at kernel/cred.c:434!
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On 04/17, Paul Moore wrote:
>
> I'm tempted to simply return an error in selinux_setprocattr() if
> the task's credentials are not the same as its real_cred;

What about other modules? I have no idea what smack_setprocattr() is,
but it too does prepare_creds/commit creds.

it seems that the simplest workaround should simply add the additional
cred == real_cred into proc_pid_attr_write().

Oleg.