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Subject: Re: [PATCH] LSM: add NULL check for kcalloc()
Cc:     linux-security-module <linux-security-module@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        kernel-team@lge.com
References: <20210712234434.GA29205@raspberrypi>
 <e0a2655b-3bc6-fd45-bd84-8df2dc6bc5f@namei.org>
 <CADLLry6RmSDuB4nmVKDEiqxXmEU0xrhMn2wieuuVTypMWqc4cQ@mail.gmail.com>
From:   Ken Goldman <kgold@linux.ibm.com>
Message-ID: <b58ae08c-c3b9-12a9-f862-bebfed8a01f2@linux.ibm.com>
Date:   Fri, 6 Aug 2021 14:33:25 -0400
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On 7/14/2021 5:44 PM, Austin Kim wrote:
> 2021=EB=85=84 7=EC=9B=94 15=EC=9D=BC (=EB=AA=A9) =EC=98=A4=EC=A0=84 4:1=
2, James Morris <jmorris@namei.org>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:=

>>
>> On Tue, 13 Jul 2021, Austin Kim wrote:
>>
>>> From: Austin Kim <austin.kim@lge.com>
>>>
>>> kcalloc() may return NULL when memory allocation fails.
>>> So it is necessary to add NULL check after the call to kcalloc() is m=
ade.
>>>
>>> Signed-off-by: Austin Kim <austin.kim@lge.com>
>>> ---
>>>   security/security.c | 2 ++
>>>   1 file changed, 2 insertions(+)
>>>
>>> diff --git a/security/security.c b/security/security.c
>>> index 09533cbb7221..f885c9e9bc35 100644
>>> --- a/security/security.c
>>> +++ b/security/security.c
>>> @@ -321,6 +321,8 @@ static void __init ordered_lsm_init(void)
>>>
>>>        ordered_lsms =3D kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),=

>>>                                GFP_KERNEL);
>>> +     if (ordered_lsms)
>>> +             return;
>>
>> Your logic is reversed here.
>=20
> I feel very sorry for my terrible mistake.
> 'if (ordered_lsms)' should have been 'if (!ordered_lsms)'.
>=20

I know it's a bit more typing, but

	if (ordered_lsms =3D=3D NULL)

compiles down to the same binary and avoids there errors that
try to treat a pointer as a boolean.


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