linux-kernel - Re: [PATCH AUTOSEL 4.19 174/258] livepatch: check kzalloc return values

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Date:   Mon, 28 Jan 2019 13:12:38 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Nicholas Mc Guire <hofrat@...dl.org>,
        Jiri Kosina <jkosina@...e.cz>, live-patching@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 4.19 174/258] livepatch: check kzalloc return
 values

On Mon, Jan 28, 2019 at 06:28:14PM +0100, Miroslav Benes wrote:
>On Mon, 28 Jan 2019, Sasha Levin wrote:
>
>> From: Nicholas Mc Guire <hofrat@...dl.org>
>>
>> [ Upstream commit 5f30b2e823484ce6a79f2b59901b6351c15effa6 ]
>>
>> kzalloc() return should always be checked - notably in example code
>> where this may be seen as reference. On failure of allocation in
>> livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous
>> allocation is freed (thanks to Petr Mladek <pmladek@...e.com> for
>> catching this) and NULL returned.
>>
>> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
>> Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API")
>> Acked-by: Joe Lawrence <joe.lawrence@...hat.com>
>> Reviewed-by: Petr Mladek <pmladek@...e.com>
>> Acked-by: Miroslav Benes <mbenes@...e.cz>
>> Signed-off-by: Jiri Kosina <jkosina@...e.cz>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>
>Hi Sasha,
>
>I am not sure what stable policy is, but the patch is for samples/
>directory and I do not think it is something which should necessarily go
>to stable. It is your call though.

The thing with samples/ is that (I'm hopefull that) the code that lives
in there is being used as a basis for userspace code and is copy&pasted
shamelessly.

So on one hand, yes, samples/ isn't exactly critical code, but on the
other hand it's also very unlikely to cause a regression, so I've been
treating it similarily to tools/testing/.

If anyone disagrees I'd be happy to discuss it.

--
Thanks,
Sasha