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Received: from relay9-d.mail.gandi.net ([217.70.183.199]) by casper.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hUtcT-0006TG-B9; Sun, 26 May 2019 13:55:27 +0000 X-Originating-IP: 79.86.19.127 Received: from alex.numericable.fr (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay9-d.mail.gandi.net (Postfix) with ESMTPSA id 3D31BFF805; Sun, 26 May 2019 13:54:47 +0000 (UTC) From: Alexandre Ghiti To: Andrew Morton Subject: [PATCH v4 06/14] arm: Properly account for stack randomization and stack guard gap Date: Sun, 26 May 2019 09:47:38 -0400 Message-Id: <20190526134746.9315-7-alex@ghiti.fr> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190526134746.9315-1-alex@ghiti.fr> References: <20190526134746.9315-1-alex@ghiti.fr> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190526_145525_397587_A6976EEE X-CRM114-Status: GOOD ( 12.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Kees Cook , Alexandre Ghiti , Catalin Marinas , Palmer Dabbelt , Will Deacon , Russell King , Ralf Baechle , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Paul Burton , Alexander Viro , James Hogan , linux-fsdevel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mips@vger.kernel.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Luis Chamberlain Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: Kees Cook --- arch/arm/mm/mmap.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index f866870db749..bff3d00bda5b 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -18,8 +18,9 @@ (((pgoff)<> (PAGE_SHIFT - 12)) static int mmap_is_legacy(struct rlimit *rlim_stack) { @@ -35,6 +36,15 @@ 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;