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From: Alexandre Ghiti <alex@ghiti.fr>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
	Kees Cook <keescook@chromium.org>,
	Alexandre Ghiti <alex@ghiti.fr>,
	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-mm@kvack.org,
	Luis Chamberlain <mcgrof@kernel.org>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>,
	linux-fsdevel@vger.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: [PATCH v5 03/14] arm64: Consider stack randomization for mmap base only when necessary
Date: Tue, 30 Jul 2019 01:51:02 -0400
Message-ID: <20190730055113.23635-4-alex@ghiti.fr> (raw)
In-Reply-To: <20190730055113.23635-1-alex@ghiti.fr>

Do not offset mmap base address because of stack randomization if
current task does not want randomization.
Note that x86 already implements this behaviour.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
---
 arch/arm64/mm/mmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index bb0140afed66..e4acaead67de 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -54,7 +54,11 @@ unsigned long arch_mmap_rnd(void)
 static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
 {
 	unsigned long gap = rlim_stack->rlim_cur;
-	unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap;
+	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)
-- 
2.20.1


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  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-30  5:50 [PATCH v5 00/14] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 01/14] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 02/14] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-07-30  5:51 ` Alexandre Ghiti [this message]
2019-07-30  5:51 ` [PATCH v5 04/14] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 06/14] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 07/14] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 08/14] arm: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 09/14] mips: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 10/14] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 11/14] mips: Adjust brk randomization offset to fit generic version Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 12/14] mips: Replace arch specific way to determine 32bit task with " Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 13/14] mips: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-07-30  5:51 ` [PATCH v5 14/14] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-07-31  6:05   ` Alex Ghiti
2019-07-31 17:33     ` Guenter Roeck
2019-07-31 22:40   ` Paul Walmsley

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