linux-kernel - Re: [PATCH] KEYS: trusted: fix crash when TPM/TEE are built as module

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Date:   Mon, 7 Feb 2022 15:12:45 -0800
From:   Tong Zhang <ztong0001@...il.com>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc:     James Bottomley <jejb@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        David Howells <dhowells@...hat.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Sumit Garg <sumit.garg@...aro.org>,
        linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>,
        Andreas Rammhold <andreas@...mhold.de>
Subject: Re: [PATCH] KEYS: trusted: fix crash when TPM/TEE are built as module

On Sun, Feb 6, 2022 at 2:36 AM Ahmad Fatoum <a.fatoum@...gutronix.de> wrote:
>
> Hello Tong,
>
> On 04.02.22 21:03, Tong Zhang wrote:
> > when TCG_TPM and TEE are built as module, trusted_key_sources will be an
> > empty array, loading it won't do what it is supposed to do and unloading
> > it will cause kernel crash.
>
> Jarkko reported picking up an equivalent fix two months ago:
> https://lkml.kernel.org/keyrings/YadRAWbl2aiapf8l@iki.fi/
>
> But it seems to have never made it to Linus.
>
> Cheers,
> Ahmad
>
> >
> > To reproduce:
> > $ modprobe trusted
> > $ modprobe -r trusted
> >
> > [  173.749423] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > [  173.755268] Backtrace:
> > [  173.755378]  cleanup_trusted [trusted] from sys_delete_module+0x15c/0x22c
> > [  173.755589]  sys_delete_module from ret_fast_syscall+0x0/0x1c
> >
> > To fix this issue, we also need to check CONFIG_TCG_TPM_MODULE and
> > CONFIG_TEE_MODULE.
> >
> > Fixes: 5d0682be3189 ("KEYS: trusted: Add generic trusted keys framework")
> > Signed-off-by: Tong Zhang <ztong0001@...il.com>
> > ---
> >  security/keys/trusted-keys/trusted_core.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> > index d5c891d8d353..b3a3b2f2d4a4 100644
> > --- a/security/keys/trusted-keys/trusted_core.c
> > +++ b/security/keys/trusted-keys/trusted_core.c
> > @@ -27,10 +27,10 @@ module_param_named(source, trusted_key_source, charp, 0);
> >  MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");
> >
> >  static const struct trusted_key_source trusted_key_sources[] = {
> > -#if defined(CONFIG_TCG_TPM)
> > +#if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)
> >       { "tpm", &trusted_key_tpm_ops },
> >  #endif
> > -#if defined(CONFIG_TEE)
> > +#if defined(CONFIG_TEE) || defined(CONFIG_TEE_MODULE)
> >       { "tee", &trusted_key_tee_ops },
> >  #endif
> >  };
>
>
> --
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Hi Ahmad,
Thanks for letting me know.
That fix looks good to me.
- Tong