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From: Alexandre Ghiti <alex@ghiti.fr>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: 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>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
	linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, Alexandre Ghiti <alex@ghiti.fr>
Subject: [PATCH v4 09/14] mips: Properly account for stack randomization and stack guard gap
Date: Sun, 26 May 2019 09:47:41 -0400	[thread overview]
Message-ID: <20190526134746.9315-10-alex@ghiti.fr> (raw)
In-Reply-To: <20190526134746.9315-1-alex@ghiti.fr>

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>
---
 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 2f616ebeb7e0..3ff82c6f7e24 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)
+#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);
+
+	/* Values close to RLIM_INFINITY can overflow. */
+	if (gap + pad > gap)
+		gap += pad;
 
 	if (gap < MIN_GAP)
 		gap = MIN_GAP;
-- 
2.20.1


  parent reply	other threads:[~2019-05-26 13:58 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-26 13:47 [PATCH v4 00/14] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-05-26 13:47 ` [PATCH v4 01/14] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-05-26 13:47 ` [PATCH v4 02/14] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-06-03 17:32   ` Catalin Marinas
2019-05-26 13:47 ` [PATCH v4 03/14] arm64: Consider stack randomization for mmap base only when necessary Alexandre Ghiti
2019-06-03 17:37   ` Catalin Marinas
2019-05-26 13:47 ` [PATCH v4 04/14] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-05-29 20:10   ` Kees Cook
2019-06-03 17:38   ` Catalin Marinas
2019-05-26 13:47 ` [PATCH v4 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout Alexandre Ghiti
2019-05-29 20:10   ` Kees Cook
2019-06-01  9:04   ` Christoph Hellwig
2019-06-03  7:05     ` Alexandre Ghiti
2019-06-03 17:40   ` Catalin Marinas
2019-06-04  6:20     ` Alex Ghiti
2019-05-26 13:47 ` [PATCH v4 06/14] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-05-26 13:47 ` [PATCH v4 07/14] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-05-26 13:47 ` [PATCH v4 08/14] arm: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-05-29 19:26   ` Kees Cook
2019-05-31  4:49     ` Alex Ghiti
2019-05-26 13:47 ` Alexandre Ghiti [this message]
2019-05-26 13:47 ` [PATCH v4 10/14] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-05-26 13:47 ` [PATCH v4 11/14] mips: Adjust brk randomization offset to fit generic version Alexandre Ghiti
2019-05-29 20:12   ` Kees Cook
2019-05-26 13:47 ` [PATCH v4 12/14] mips: Replace arch specific way to determine 32bit task with " Alexandre Ghiti
2019-05-29 20:12   ` Kees Cook
2019-05-26 13:47 ` [PATCH v4 13/14] mips: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-05-29 20:12   ` Kees Cook
2019-05-26 13:47 ` [PATCH v4 14/14] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-05-29 20:16 ` [PATCH v4 00/14] Provide generic top-down mmap layout functions Kees Cook
2019-05-31  5:04   ` Alex Ghiti
2019-06-13  5:29 ` Alex Ghiti
2019-06-30 15:34   ` Alex Ghiti

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