linux-kernel - Re: [PATCH v2] KEYS: prevent NULL pointer dereference in find_asymmetric

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Message-ID: <85607ea7-a42a-1c7b-0722-e4b63a814385@omp.ru>
Date: Wed, 11 Sep 2024 17:45:49 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Jarkko Sakkinen <jarkko@...nel.org>, Roman Smirnov <r.smirnov@....ru>,
	David Howells <dhowells@...hat.com>, Herbert Xu
	<herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>,
	Andrew Zaborowski <andrew.zaborowski@...el.com>
CC: <keyrings@...r.kernel.org>, <linux-crypto@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: Re: [PATCH v2] KEYS: prevent NULL pointer dereference in
 find_asymmetric_key()

On 9/11/24 4:19 PM, Jarkko Sakkinen wrote:

[...]

>>>>> In find_asymmetric_key(), if all NULLs are passed in id_{0,1,2} parameters
>>>>> the kernel will first emit WARN and then have an oops because id_2 gets
>>>>> dereferenced anyway.
>>>>>
>>>>> Found by Linux Verification Center (linuxtesting.org) with Svace static
>>>>> analysis tool.
>>>>
>>>> Weird, I recall that I've either sent a patch to address the same site
>>>> OR have commented a patch with similar reasoning. Well, it does not
>>>> matter, I think it this makes sense to me.
>>>>
>>>> You could further add to the motivation that given the panic_on_warn
>>>> kernel command-line parameter, it is for the best limit the scope and
>>>> use of the WARN-macro.
>>>
>>>    I don't understand what you mean -- this version of the patch keeps
>>> the WARN_ON() call, it just moves that call, so that the duplicate id_{0,1,2}
>>> checks are avoided...
>>
>> I overlooked the code change (my bad sorry). Here's a better version of
>> the first paragraph:
>>
>> "find_asymmetric_keys() has nullity checks of id_0 and id_1 but ignores
>> validation for id_2. Check nullity also for id_2."
>>
>> Yep, and it changes no situation with WARN_ON() macro for better or
>> worse. It would logically separate issue to discuss and address so
>> as far as I'm concerned, with this clarification I think the change
>> makes sense to me.
> 
> Actually explicitly stating that call paths leading to WARN_ON()
> invocation are intact by the commit (as a reminder for future).

   OK...
   Do you still think the Fixes tag should be dropped (and thus the
Reported-by tag would become unnecessary?)?

> BR, Jarkko

MBR, Sergey