From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH v3 04/10] mips: extract logic for mmap_rnd() Date: Tue, 3 Mar 2015 18:10:19 -0800 Message-ID: <1425435025-30284-5-git-send-email-keescook@chromium.org> References: <1425435025-30284-1-git-send-email-keescook@chromium.org> Cc: Kees Cook , linux-kernel@vger.kernel.org, Hector Marco-Gisbert , Ismael Ripoll , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, x86@kernel.org, Alexander Viro , Oleg Nesterov , Andy Lutomirski , "David A. Long" , Andrey Ryabinin , Arun Chandran < To: akpm@linux-foundation.org Return-path: In-Reply-To: <1425435025-30284-1-git-send-email-keescook@chromium.org> Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: List-Id: linux-fsdevel.vger.kernel.org In preparation for splitting out ET_DYN ASLR, extract the mmap ASLR selection into a separate function. Signed-off-by: Kees Cook --- arch/mips/mm/mmap.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index f1baadd56e82..673a5cfe082f 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -142,18 +142,26 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, addr0, len, pgoff, flags, DOWN); } +static unsigned long mmap_rnd(void) +{ + unsigned long rnd; + + rnd = (unsigned long)get_random_int(); + rnd <<= PAGE_SHIFT; + if (TASK_IS_32BIT_ADDR) + random_factor &= 0xfffffful; + else + random_factor &= 0xffffffful; + + return rnd; +} + void arch_pick_mmap_layout(struct mm_struct *mm) { unsigned long random_factor = 0UL; - if (current->flags & PF_RANDOMIZE) { - random_factor = get_random_int(); - random_factor = random_factor << PAGE_SHIFT; - if (TASK_IS_32BIT_ADDR) - random_factor &= 0xfffffful; - else - random_factor &= 0xffffffful; - } + if (current->flags & PF_RANDOMIZE) + random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; -- 1.9.1