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@xxxxxxxxx>
[ 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@xxxxxxxxx>
...
---
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
