From: Matthew Wilcox <willy@infradead.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>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH] mm/vmalloc: randomize vmalloc() allocations
Date: Wed, 2 Dec 2020 18:53:34 +0000 [thread overview]
Message-ID: <20201202185334.GG11935@casper.infradead.org> (raw)
In-Reply-To: <20201201214547.9721-1-toiwoton@gmail.com>
On Tue, Dec 01, 2020 at 11:45:47PM +0200, Topi Miettinen wrote:
> + /* Randomize allocation */
> + if (randomize_vmalloc) {
> + voffset = get_random_long() & (roundup_pow_of_two(vend - vstart) - 1);
> + voffset = PAGE_ALIGN(voffset);
> + if (voffset + size > vend - vstart)
> + voffset = vend - vstart - size;
> + } else
> + voffset = 0;
> +
> /*
> * If an allocation fails, the "vend" address is
> * returned. Therefore trigger the overflow path.
> */
> - addr = __alloc_vmap_area(size, align, vstart, vend);
> + addr = __alloc_vmap_area(size, align, vstart + voffset, vend);
> spin_unlock(&free_vmap_area_lock);
What if there isn't any free address space between vstart+voffset and
vend, but there is free address space between vstart and voffset?
Seems like we should add:
addr = __alloc_vmap_area(size, align, vstart + voffset, vend);
+ if (!addr)
+ addr = __alloc_vmap_area(size, align, vstart, vend);
spin_unlock(&free_vmap_area_lock);
next prev parent reply other threads:[~2020-12-02 18:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 21:45 [PATCH] mm/vmalloc: randomize vmalloc() allocations Topi Miettinen
2020-12-02 18:49 ` Topi Miettinen
2020-12-03 6:58 ` Mike Rapoport
2020-12-03 23:15 ` David Laight
2020-12-04 10:58 ` Topi Miettinen
2020-12-04 13:33 ` David Laight
2020-12-04 16:53 ` Topi Miettinen
2020-12-09 19:08 ` Topi Miettinen
2020-12-10 19:58 ` Topi Miettinen
2020-12-02 18:53 ` Matthew Wilcox [this message]
2020-12-02 21:28 ` Topi Miettinen
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