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Subject: Re: [RFC PATCH 2/2] integrity: double check iint_cache was
 initialized
To:     Dmitry Vyukov <dvyukov@google.com>,
        Mimi Zohar <zohar@linux.ibm.com>
Cc:     linux-integrity@vger.kernel.org, James Morris <jmorris@namei.org>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Eric Biggers <ebiggers@kernel.org>
References: <20210319200358.22816-1-zohar@linux.ibm.com>
 <20210319200358.22816-2-zohar@linux.ibm.com>
 <8450c80a-104a-3f36-0963-0ae8fa69e0f2@i-love.sakura.ne.jp>
 <CACT4Y+bvakfNhVs29QvbY6Z8Pw0zmAUKGWM-DD5DcPZW5ny90A@mail.gmail.com>
From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Message-ID: <1a2245c6-3cab-7085-83d3-55b083619303@i-love.sakura.ne.jp>
Date:   Tue, 23 Mar 2021 10:46:52 +0900
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On 2021/03/20 5:03, Mimi Zohar wrote:
> The integrity's "iint_cache" is initialized at security_init().  Only
> after an IMA policy is loaded, which is initialized at late_initcall,
> is a file's integrity status stored in the "iint_cache".
> 
> All integrity_inode_get() callers first verify that the IMA policy has
> been loaded, before calling it.  Yet for some reason, it is still being
> called, causing a NULL pointer dereference.
> 
> qemu-system-x86_64 (...snipped...) lsm=smack (...snipped...)

Hmm, why are you using lsm=smack instead of security=smack ?
Since use of lsm= overrides CONFIG_LSM="lockdown,yama,safesetid,integrity,tomoyo,smack,bpf" settings,
only smack is activated, which means that integrity_iintcache_init() will not be called by

  DEFINE_LSM(integrity) = {
  	.name = "integrity",
  	.init = integrity_iintcache_init,
  };

declaration. That's the reason iint_cache == NULL when integrity_inode_get() is called.