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arm64, mm: make randomization selected by generic topdown mmap layout

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This commits selects ARCH_HAS_ELF_RANDOMIZE when an arch uses the generic
topdown mmap layout functions so that this security feature is on by
default.

Note that this commit also removes the possibility for arm64 to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.

Link: http://lkml.kernel.org/r/20190730055113.23635-6-alex@ghiti.fr
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>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.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>
This commit is contained in:
Alexandre Ghiti
2019-09-23 15:38:50 -07:00
committed by Linus Torvalds
parent 67f3977f80
commit e7142bf5d2
4 changed files with 10 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
arch/arm64/kernel/process.c
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@@ -557,14 +557,6 @@ unsigned long arch_align_stack(unsigned long sp)
return sp & ~0xf;
}
unsigned long arch_randomize_brk(struct mm_struct *mm)
{
if (is_compat_task())
return randomize_page(mm->brk, SZ_32M);
else
return randomize_page(mm->brk, SZ_1G);
}
/*
* Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
*/