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Date:   Wed, 30 Jan 2019 09:56:22 +0100
From:   Petr Mladek <pmladek@suse.com>
To:     Joe Lawrence <joe.lawrence@redhat.com>
Cc:     Jiri Kosina <jikos@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Miroslav Benes <mbenes@suse.cz>,
        Jason Baron <jbaron@akamai.com>,
        Evgenii Shatokhin <eshatokhin@virtuozzo.com>,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] livepatch: Handle failing allocation of shadow
 variables in the selftest
Message-ID: <20190130085622.y4de47nekrhy4pmq@pathway.suse.cz>
References: <20190116161720.796-1-pmladek@suse.com>
 <20190116161720.796-3-pmladek@suse.com>
 <20190121224012.GB8766@redhat.com>
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On Mon 2019-01-21 17:40:12, Joe Lawrence wrote:
> 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.

Accessing an invalid pointer would crash the kernel.


> 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.

As I wrote in the replay to Miroslav. The best practice is to
handle errors everywhere. I am going to do so in v2. People
might use it as a sample...

Best Regards,
Petr