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From:   Mike Rapoport <rppt@kernel.org>
To:     Topi Miettinen <toiwoton@gmail.com>
Cc:     linux-hardening@vger.kernel.org, akpm@linux-foundation.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@kernel.org>,
        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Linux API <linux-api@vger.kernel.org>,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH] mm/vmalloc: randomize vmalloc() allocations
Message-ID: <20201203065801.GH751215@kernel.org>
References: <20201201214547.9721-1-toiwoton@gmail.com>
 <9d34fb0a-7aba-1e84-6426-006ea7c3d9f5@gmail.com>
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On Wed, Dec 02, 2020 at 08:49:06PM +0200, Topi Miettinen wrote:
> On 1.12.2020 23.45, Topi Miettinen wrote:
> > Memory mappings inside kernel allocated with vmalloc() are in
> > predictable order and packed tightly toward the low addresses. With
> > new kernel boot parameter 'randomize_vmalloc=1', the entire area is
> > used randomly to make the allocations less predictable and harder to
> > guess for attackers.
> > 
> 
> This also seems to randomize module addresses. I was going to check that
> next, so nice surprise!

Heh, that's because module_alloc() uses vmalloc() in that way or another :)

> -Topi
> 
> >   	spin_unlock(&free_vmap_area_lock);
> >   	if (unlikely(addr == vend))
> > 
> 

-- 
Sincerely yours,
Mike.