From: Kees Cook <keescook@chromium.org>
To: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ralf Baechle <ralf@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
James Hogan <jhogan@kernel.org>,
Palmer Dabbelt <palmer@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH v3 05/11] arm: Properly account for stack randomization and stack guard gap
Date: Thu, 18 Apr 2019 00:26:11 -0500 [thread overview]
Message-ID: <CAGXu5j+V_kJk-Lu=u82CrA291EPpgJtX951EKigprozXt7=ORA@mail.gmail.com> (raw)
In-Reply-To: <20190417052247.17809-6-alex@ghiti.fr>
On Wed, Apr 17, 2019 at 12:28 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>
> This commit takes care of stack randomization and stack guard gap when
> computing mmap base address and checks if the task asked for randomization.
> This fixes the problem uncovered and not fixed for arm here:
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1429066.html
Please use the official archive instead. This includes headers, linked
patches, etc:
https://lkml.kernel.org/r/20170622200033.25714-1-riel@redhat.com
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> ---
> arch/arm/mm/mmap.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
> index f866870db749..bff3d00bda5b 100644
> --- a/arch/arm/mm/mmap.c
> +++ b/arch/arm/mm/mmap.c
> @@ -18,8 +18,9 @@
> (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
>
> /* gap between mmap and stack */
> -#define MIN_GAP (128*1024*1024UL)
> -#define MAX_GAP ((TASK_SIZE)/6*5)
> +#define MIN_GAP (128*1024*1024UL)
Might as well fix this up as SIZE_128M
> +#define MAX_GAP ((TASK_SIZE)/6*5)
> +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
STACK_RND_MASK is already defined so you don't need to add it here, yes?
> static int mmap_is_legacy(struct rlimit *rlim_stack)
> {
> @@ -35,6 +36,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack)
> static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
> {
> unsigned long gap = rlim_stack->rlim_cur;
> + unsigned long pad = stack_guard_gap;
> +
> + /* Account for stack randomization if necessary */
> + if (current->flags & PF_RANDOMIZE)
> + pad += (STACK_RND_MASK << PAGE_SHIFT);
> +
> + /* Values close to RLIM_INFINITY can overflow. */
> + if (gap + pad > gap)
> + gap += pad;
>
> if (gap < MIN_GAP)
> gap = MIN_GAP;
> --
> 2.20.1
>
But otherwise, yes:
Acked-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2019-04-18 5:26 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 5:22 [PATCH v3 00/11] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-04-17 5:22 ` [PATCH v3 01/11] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-04-18 5:20 ` Kees Cook
2019-04-17 5:22 ` [PATCH v3 02/11] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-04-18 4:32 ` Kees Cook
2019-04-18 5:23 ` Alex Ghiti
2019-04-22 19:53 ` Christoph Hellwig
2019-04-17 5:22 ` [PATCH v3 03/11] arm64: Consider stack randomization for mmap base only when necessary Alexandre Ghiti
2019-04-18 4:37 ` Kees Cook
2019-04-18 5:24 ` Alex Ghiti
2019-04-22 19:53 ` Christoph Hellwig
2019-04-17 5:22 ` [PATCH v3 04/11] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-04-18 5:17 ` Kees Cook
2019-04-18 5:55 ` Alex Ghiti
2019-04-18 14:19 ` Kees Cook
2019-04-19 7:20 ` Alex Ghiti
2019-04-22 19:55 ` Christoph Hellwig
2019-04-28 14:27 ` Alex Ghiti
2019-04-22 19:54 ` Christoph Hellwig
2019-04-17 5:22 ` [PATCH v3 05/11] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-04-18 5:26 ` Kees Cook [this message]
2019-04-18 6:01 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 06/11] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-04-18 5:27 ` Kees Cook
2019-04-18 6:04 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 07/11] arm: Use generic mmap top-down layout Alexandre Ghiti
2019-04-18 5:28 ` Kees Cook
2019-04-18 6:06 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 08/11] mips: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-04-18 5:30 ` Kees Cook
2019-04-18 6:06 ` Alex Ghiti
2019-04-18 21:27 ` Paul Burton
2019-04-19 7:20 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 09/11] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-04-18 5:31 ` Kees Cook
2019-04-18 6:08 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 10/11] mips: Use generic mmap top-down layout Alexandre Ghiti
2019-04-18 5:31 ` Kees Cook
2019-04-18 6:08 ` Alex Ghiti
2019-04-17 5:22 ` [PATCH v3 11/11] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-04-18 5:31 ` Kees Cook
2019-04-18 6:09 ` Alex Ghiti
2019-04-22 19:56 ` Christoph Hellwig
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