linux-kernel - Re: [PATCH v2 1/2] ima: Free IMA measurement buffer on error

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Message-ID: <b8573374-86d0-f679-6c9f-a61b2bc6f7ea@linux.microsoft.com>
Date:   Fri, 5 Feb 2021 09:59:45 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Greg KH <gregkh@...uxfoundation.org>
Cc:     bauerman@...ux.ibm.com, dmitry.kasatkin@...il.com,
        ebiederm@...ssion.com, sashal@...nel.org,
        tyhicks@...ux.microsoft.com, linux-integrity@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] ima: Free IMA measurement buffer on error

On 2/5/21 9:49 AM, Mimi Zohar wrote:

Hi Mimi,

> On Fri, 2021-02-05 at 09:39 -0800, Lakshmi Ramasubramanian wrote:
>> On 2/5/21 2:05 AM, Greg KH wrote:
>>> On Thu, Feb 04, 2021 at 09:49:50AM -0800, Lakshmi Ramasubramanian wrote:
>>>> IMA allocates kernel virtual memory to carry forward the measurement
>>>> list, from the current kernel to the next kernel on kexec system call,
>>>> in ima_add_kexec_buffer() function.  In error code paths this memory
>>>> is not freed resulting in memory leak.
>>>>
>>>> Free the memory allocated for the IMA measurement list in
>>>> the error code paths in ima_add_kexec_buffer() function.
>>>>
>>>> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
>>>> Suggested-by: Tyler Hicks <tyhicks@...ux.microsoft.com>
>>>> Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
>>>> ---
>>>>    security/integrity/ima/ima_kexec.c | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>
>>> <formletter>
>>>
>>> This is not the correct way to submit patches for inclusion in the
>>> stable kernel tree.  Please read:
>>>       https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>>> for how to do this properly.
>>>
>>> </formletter>
>>>
>>
>> Thanks for the info Greg.
>>
>> I will re-submit the two patches in the proper format.
> 
> No need.  I'm testing these patches now.  I'm not exactly sure what the
> problem is.  Stable wasn't Cc'ed.  Is it that you sent the patch
> directly to Greg or added "Fixes"?
> 
I had not Cced stable, but had "Fixes" tag in the patch.

Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")

The problem is that the buffer allocated for forwarding the IMA 
measurement list is not freed - at the end of the kexec call and also in 
an error path. Please see the patch description for

[PATCH v2 2/2] ima: Free IMA measurement buffer after kexec syscall

IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  This buffer is not freed before
completing the kexec system call resulting in memory leak.

thanks,
  -lakshmi