Messages in this thread | | | Subject | Re: [PATCH AUTOSEL 5.3 169/203] x86/platform/uv: Fix kmalloc() NULL check routine | From | Mike Travis <> | Date | Wed, 2 Oct 2019 07:35:59 -0700 |
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On 10/2/2019 1:34 AM, David Laight wrote: > From: Sasha Levin >> Sent: 01 October 2019 17:06 >> 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@gmail.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@gmail.com> > ... >>>> --- >>>> 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 :( > > Mind you, the code itself if pretty horrid. > Looks like it is aligning to 32 bytes, easier done by: > pqp = (void *)((unsigned long)vp + 31 & ~31); > (and there's a roundup macro to obfuscate it somewhere.) > But I'd also expect to see a matching '+ 31' in the size passed to kmalloc(). > Not to mention a comment! > > David > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) >
Thanks, I will put all of these comments in my notes. This whole function is slated to move to a specialized UV APIC driver since it uses a unique scaling feature available in the UV hardware. (The original author has long retired.)
-Mike
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