From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Alexandre Ghiti <alex@ghiti.fr>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
Kees Cook <keescook@chromium.org>,
linux-mm@kvack.org, Catalin Marinas <catalin.marinas@arm.com>,
Palmer Dabbelt <palmer@sifive.com>,
Will Deacon <will.deacon@arm.com>,
Russell King <linux@armlinux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Luis Chamberlain <mcgrof@kernel.org>,
Paul Burton <paul.burton@mips.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
James Hogan <jhogan@kernel.org>,
linux-riscv@lists.infradead.org, linux-mips@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v6 09/14] mips: Properly account for stack randomization and stack guard gap
Date: Thu, 8 Aug 2019 12:16:04 +0300 [thread overview]
Message-ID: <bd67507e-8a5b-34b5-1a33-5500bbb724b2@cogentembedded.com> (raw)
In-Reply-To: <20190808061756.19712-10-alex@ghiti.fr>
Hello!
On 08.08.2019 9:17, Alexandre Ghiti 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://lkml.kernel.org/r/20170622200033.25714-1-riel@redhat.com
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: Kees Cook <keescook@chromium.org>
> Acked-by: Paul Burton <paul.burton@mips.com>
> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
> ---
> arch/mips/mm/mmap.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
> index d79f2b432318..f5c778113384 100644
> --- a/arch/mips/mm/mmap.c
> +++ b/arch/mips/mm/mmap.c
> @@ -21,8 +21,9 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
> EXPORT_SYMBOL(shm_align_mask);
>
> /* gap between mmap and stack */
> -#define MIN_GAP (128*1024*1024UL)
> -#define MAX_GAP ((TASK_SIZE)/6*5)
> +#define MIN_GAP (128*1024*1024UL)
> +#define MAX_GAP ((TASK_SIZE)/6*5)
Could add spaces around *, while touching this anyway? And parens
around TASK_SIZE shouldn't be needed...
> +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
>
> static int mmap_is_legacy(struct rlimit *rlim_stack)
> {
> @@ -38,6 +39,15 @@ 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);
Parens not needed here.
> +
> + /* Values close to RLIM_INFINITY can overflow. */
> + if (gap + pad > gap)
> + gap += pad;
>
> if (gap < MIN_GAP)
> gap = MIN_GAP;
>
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next prev parent reply other threads:[~2019-08-08 9:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 6:17 [PATCH v6 00/14] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 01/14] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 02/14] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 03/14] arm64: Consider stack randomization for mmap base only when necessary Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 04/14] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 06/14] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 07/14] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 08/14] arm: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 09/14] mips: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-08-08 9:16 ` Sergei Shtylyov [this message]
2019-08-09 9:44 ` Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 10/14] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 11/14] mips: Adjust brk randomization offset to fit generic version Alexandre Ghiti
2019-08-08 9:19 ` Sergei Shtylyov
2019-08-09 9:45 ` Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 12/14] mips: Replace arch specific way to determine 32bit task with " Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 13/14] mips: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 14/14] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-10-05 2:12 ` Atish Patra
2019-10-07 9:11 ` Alex Ghiti
2019-10-08 0:46 ` Atish Patra
2019-10-08 11:58 ` Alex Ghiti
2019-10-09 2:07 ` Atish Patra
2019-10-09 18:39 ` Alex Ghiti
2019-10-15 0:31 ` Atish Patra
2019-10-08 9:19 ` Alex Ghiti
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