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Sat, 12 Oct 2019 05:29:55 -0700 (PDT) Received: from localhost.localdomain ([2402:3a80:95a:fd75:24a6:4bd:55a6:4f65]) by smtp.gmail.com with ESMTPSA id v8sm33708697pje.6.2019.10.12.05.29.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Oct 2019 05:29:54 -0700 (PDT) From: Shyam Saini To: kernel-hardening@lists.openwall.com Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Shyam Saini , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Matthew Wilcox , Christopher Lameter , Kees Cook Subject: [PATCH] kernel: dma: Make CMA boot parameters __ro_after_init Date: Sat, 12 Oct 2019 17:59:18 +0530 Message-Id: <20191012122918.8066-1-mayhs11saini@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This parameters are not changed after early boot. By making them __ro_after_init will reduce any attack surface in the kernel. Link: https://lwn.net/Articles/676145/ Cc: Christoph Hellwig Cc: Marek Szyprowski Cc: Robin Murphy Cc: Matthew Wilcox Cc: Christopher Lameter Cc: Kees Cook Signed-off-by: Shyam Saini --- kernel/dma/contiguous.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 69cfb4345388..1b689b1303cd 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -42,10 +42,10 @@ struct cma *dma_contiguous_default_area; * Users, who want to set the size of global CMA area for their system * should use cma= kernel parameter. */ -static const phys_addr_t size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; -static phys_addr_t size_cmdline = -1; -static phys_addr_t base_cmdline; -static phys_addr_t limit_cmdline; +static const phys_addr_t __ro_after_init size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; +static phys_addr_t __ro_after_init size_cmdline = -1; +static phys_addr_t __ro_after_init base_cmdline; +static phys_addr_t __ro_after_init limit_cmdline; static int __init early_cma(char *p) {