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