Message-ID: <4DFCF13F.50401@cslab.ece.ntua.gr>
Date: Sat, 18 Jun 2011 21:41:03 +0300
From: Vasileios Karakasis <bkk@cslab.ece.ntua.gr>
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To: Andi Kleen <andi@firstfloor.org>
CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-numa@vger.kernel.org
Subject: Re: [BUG] Invalid return address of mmap() followed by mbind() in
 multithreaded context
References: <4DFB710D.7000902@cslab.ece.ntua.gr> <20110618181232.GI16236@one.firstfloor.org>
In-Reply-To: <20110618181232.GI16236@one.firstfloor.org>
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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 =3D 0; i < NR_ITER; i++) {
>>         addr =3D mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE,
>>                     MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
>>         if (addr =3D=3D (void *) -1) {
>>             assert(0 && "mmap failed");
>>         }
>>         *addr =3D 0;
>>
>>         err =3D mbind(addr, PAGE_SIZE, MPOL_BIND, &node, sizeof(node),=
 0);
>=20
> mbind() can be only done before the first touch. you're not actually te=
sting=20
> numa policy.
>=20
> -andi

--=20
V.K.


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