linux-kernel - Re: [PATCH AUTOSEL 5.3 169/203] x86/platform/uv: Fix kmalloc() NULL check routine

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Date:   Tue, 1 Oct 2019 12:06:01 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Austin Kim <austindh.kim@...il.com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Hedi Berriche <hedi.berriche@....com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Travis <mike.travis@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Russ Anderson <russ.anderson@....com>,
        Steve Wahl <steve.wahl@....com>,
        Thomas Gleixner <tglx@...utronix.de>, allison@...utok.net,
        andy@...radead.org, armijn@...ldur.nl, bp@...en8.de,
        dvhart@...radead.org, hpa@...or.com, kjlu@....edu,
        platform-driver-x86@...r.kernel.org, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH AUTOSEL 5.3 169/203] x86/platform/uv: Fix kmalloc() NULL
 check routine

On Sun, Sep 22, 2019 at 10:25:44PM +0200, Greg KH wrote:
>On Sun, Sep 22, 2019 at 02:43:15PM -0400, Sasha Levin wrote:
>> From: Austin Kim <austindh.kim@...il.com>
>>
>> [ Upstream commit 864b23f0169d5bff677e8443a7a90dfd6b090afc ]
>>
>> The result of kmalloc() should have been checked ahead of below statement:
>>
>> 	pqp = (struct bau_pq_entry *)vp;
>>
>> Move BUG_ON(!vp) before above statement.
>>
>> Signed-off-by: Austin Kim <austindh.kim@...il.com>
>> Cc: Dimitri Sivanich <dimitri.sivanich@....com>
>> Cc: Hedi Berriche <hedi.berriche@....com>
>> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>> Cc: Mike Travis <mike.travis@....com>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Russ Anderson <russ.anderson@....com>
>> Cc: Steve Wahl <steve.wahl@....com>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: allison@...utok.net
>> Cc: andy@...radead.org
>> Cc: armijn@...ldur.nl
>> Cc: bp@...en8.de
>> Cc: dvhart@...radead.org
>> Cc: gregkh@...uxfoundation.org
>> Cc: hpa@...or.com
>> Cc: kjlu@....edu
>> Cc: platform-driver-x86@...r.kernel.org
>> Link: https://lkml.kernel.org/r/20190905232951.GA28779@LGEARND20B15
>> Signed-off-by: Ingo Molnar <mingo@...nel.org>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>> ---
>>  arch/x86/platform/uv/tlb_uv.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
>> index 20c389a91b803..5f0a96bf27a1f 100644
>> --- a/arch/x86/platform/uv/tlb_uv.c
>> +++ b/arch/x86/platform/uv/tlb_uv.c
>> @@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
>>
>>  	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
>>  	vp = kmalloc_node(plsize, GFP_KERNEL, node);
>> -	pqp = (struct bau_pq_entry *)vp;
>> -	BUG_ON(!pqp);
>> +	BUG_ON(!vp);
>>
>> +	pqp = (struct bau_pq_entry *)vp;
>>  	cp = (char *)pqp + 31;
>>  	pqp = (struct bau_pq_entry *)(((unsigned long)cp >> 5) << 5);
>>
>
>How did this even get merged in the first place?  I thought a number of
>us complained about it.
>
>This isn't any change in code, and the original is just fine, the author
>didn't realize how C works :(
>
>Please drop this.

Heh, I've dropped it.

--
Thanks,
Sasha