linux-kernel - Re: [BUG] Invalid return address of mmap() followed by mbind() in multithreaded context

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Date:	Sat, 18 Jun 2011 21:41:03 +0300
From:	Vasileios Karakasis <bkk@...ab.ece.ntua.gr>
To:	Andi Kleen <andi@...stfloor.org>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-numa@...r.kernel.org
Subject: Re: [BUG] Invalid return address of mmap() followed by mbind() in
 multithreaded context

That's right, but what I want to demonstrate is that the address
returned by mmap() is invalid and the dereference crashes the program,
while it shouldn't. I could equally omit this statement, in which case
mbind() would fail with EFAULT.

On 06/18/2011 09:12 PM, Andi Kleen wrote:
>>     for (i = 0; i < NR_ITER; i++) {
>>         addr = mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE,
>>                     MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
>>         if (addr == (void *) -1) {
>>             assert(0 && "mmap failed");
>>         }
>>         *addr = 0;
>>
>>         err = mbind(addr, PAGE_SIZE, MPOL_BIND, &node, sizeof(node), 0);
> 
> mbind() can be only done before the first touch. you're not actually testing 
> numa policy.
> 
> -andi

-- 
V.K.


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