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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1goXxi-0001R7-9f; Tue, 29 Jan 2019 18:18:18 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1goXxe-0001Qk-FH for linux-arm-kernel@lists.infradead.org; Tue, 29 Jan 2019 18:18:16 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9E84B1596; Tue, 29 Jan 2019 10:18:13 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.113]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B30EE3F557; Tue, 29 Jan 2019 10:18:12 -0800 (PST) Date: Tue, 29 Jan 2019 18:18:10 +0000 From: Catalin Marinas To: Ard Biesheuvel Subject: Re: [PATCH] arm64: kaslr: ensure randomized quantities are clean also when kaslr is off Message-ID: <20190129181809.GD224095@arrakis.emea.arm.com> References: <20190127082942.21998-1-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190127082942.21998-1-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190129_101814_516966_E240973F X-CRM114-Status: GOOD ( 20.70 ) 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: will.deacon@arm.com, stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Jan 27, 2019 at 09:29:42AM +0100, Ard Biesheuvel wrote: > Commit 1598ecda7b23 ("arm64: kaslr: ensure randomized quantities are > clean to the PoC") added cache maintenance to ensure that global > variables set by the kaslr init routine are not wiped clean due to > cache invalidation occurring during the second round of page table > creation. > > However, if kaslr_early_init() exits early with no randomization > being applied (either due to the lack of a seed, or because the user > has disabled kaslr explicitly), no cache maintenance is performed, > leading to the same issue we attempted to fix earlier, as far as the > module_alloc_base variable is concerned. > > Note that module_alloc_base cannot be initialized statically, because > that would cause it to be subject to a R_AARCH64_RELATIVE relocation, > causing it to be overwritten by the second round of KASLR relocation > processing. > > Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR") > Cc: # v4.6+ > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/kernel/kaslr.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c > index ba6b41790fcd..b09b6f75f759 100644 > --- a/arch/arm64/kernel/kaslr.c > +++ b/arch/arm64/kernel/kaslr.c > @@ -88,6 +88,7 @@ u64 __init kaslr_early_init(u64 dt_phys) > * we end up running with module randomization disabled. > */ > module_alloc_base = (u64)_etext - MODULES_VSIZE; > + __flush_dcache_area(&module_alloc_base, sizeof(module_alloc_base)); Do we need something similar of memstart_offset_seed? If yes, you could as well change the returns to a goto out. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel