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Date: Wed, 4 Mar 2015 13:10:45 -0800 From: Kees Cook <keescook@...omium.org> To: akpm@...ux-foundation.org Cc: Kees Cook <keescook@...omium.org>, Ingo Molnar <mingo@...hat.com>, Michael Ellerman <mpe@...erman.id.au>, Hector Marco-Gisbert <hecmargi@....es>, Ismael Ripoll <iripoll@....es>, Russell King <linux@....linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Ralf Baechle <ralf@...ux-mips.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, linux390@...ibm.com, x86@...nel.org, Alexander Viro <viro@...iv.linux.org.uk>, Andy Lutomirski <luto@...capital.net>, Oleg Nesterov <oleg@...hat.com>, "David A. Long" <dave.long@...aro.org>, Andrey Ryabinin <a.ryabinin@...sung.com>, Arun Chandran <achandran@...sta.com>, Yann Droneaud <ydroneaud@...eya.com>, Min-Hua Chen <orca.chen@...il.com>, Paul Burton <paul.burton@...tec.com>, Alex Smith <alex@...x-smith.me.uk>, Markos Chandras <markos.chandras@...tec.com>, Vineeth Vijayan <vvijayan@...sta.com>, Jeff Bailey <jeffbailey@...gle.com>, Michael Holzheu <holzheu@...ux.vnet.ibm.com>, Ben Hutchings <ben@...adent.org.uk>, Borislav Petkov <bp@...e.de>, Jan-Simon Möller <dl9pf@....de>, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org, linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: [PATCH v4 01/10] arm: factor out mmap ASLR into mmap_rnd In preparation for splitting out ET_DYN ASLR, this moves the ASLR calculations for mmap on ARM into a separate routine, similar to x86. This also removes the redundant check of personality (PF_RANDOMIZE is already set before calling arch_pick_mmap_layout). Signed-off-by: Kees Cook <keescook@...omium.org> --- arch/arm/mm/mmap.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index 5e85ed371364..15a8160096b3 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -169,14 +169,22 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } +static unsigned long mmap_rnd(void) +{ + unsigned long rnd; + + /* 8 bits of randomness in 20 address space bits */ + rnd = (unsigned long)get_random_int() % (1 << 8); + + return rnd << PAGE_SHIFT; +} + void arch_pick_mmap_layout(struct mm_struct *mm) { unsigned long random_factor = 0UL; - /* 8 bits of randomness in 20 address space bits */ - if ((current->flags & PF_RANDOMIZE) && - !(current->personality & ADDR_NO_RANDOMIZE)) - random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + if (current->flags & PF_RANDOMIZE) + random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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