linux-kernel - Re: [PATCH 2/4] livepatch: Handle failing allocation of shadow variables in the selftest

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Date:   Mon, 21 Jan 2019 17:40:12 -0500
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Jason Baron <jbaron@...mai.com>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] livepatch: Handle failing allocation of shadow
 variables in the selftest

On Wed, Jan 16, 2019 at 05:17:18PM +0100, Petr Mladek wrote:
> Do not dereference pointers to the shadow variables when either
> klp_shadow_alloc() or klp_shadow_get() fail.
> 
> There is no need to check the other locations explicitly. The test
> would fail if any allocation fails. And the existing messages, printed
> during the test, provide enough information to debug eventual problems.
> 

I didn't run the test under those failing conditions, but at looking at
the code, I think it would simply skip the "expected <conditions> found"
and the test script would complain about not seeing that msg.

Would it be easier to just bite the bullet and verify sv[0-4] at their
allocation sites?  Then later uses (ie, the sv3 dereference that
Miroslav spotted at the bottom) or new code wouldn't fall through the
cracks.

-- Joe