Commit e548599f authored Sep 23, 2019 by Alexandre Ghiti Committed by Linus Torvalds Sep 24, 2019

mips: adjust brk randomization offset to fit generic version

This commit simply bumps up to 32MB and 1GB the random offset of brk,
compared to 8MB and 256MB, for 32bit and 64bit respectively.

Link: http://lkml.kernel.org/r/20190730055113.23635-12-alex@ghiti.fr


Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent b5fb8617

arch/mips/mm/mmap.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		#include <linux/random.h>
		#include <linux/sched/signal.h>
		#include <linux/sched/mm.h>
		#include <linux/sizes.h>

		unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
		EXPORT_SYMBOL(shm_align_mask);
		@@ -189,11 +190,11 @@ static inline unsigned long brk_rnd(void)
		unsigned long rnd = get_random_long();

		rnd = rnd << PAGE_SHIFT;
		/* 8MB for 32bit, 256MB for 64bit */
		/* 32MB for 32bit, 1GB for 64bit */
		if (TASK_IS_32BIT_ADDR)
		rnd = rnd & 0x7ffffful;
		rnd = rnd & (SZ_32M - 1);
		else
		rnd = rnd & 0xffffffful;
		rnd = rnd & (SZ_1G - 1);

		return rnd;
		}

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