linux-kernel - [PATCH] ARM: module: Avoid W and X mappings at the beginning

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Message-ID: <1565424575-346010-1-git-send-email-zhe.he@windriver.com>
Date:   Sat, 10 Aug 2019 16:09:35 +0800
From:   <zhe.he@...driver.com>
To:     <linux@...linux.org.uk>, <ast@...nel.org>, <daniel@...earbox.net>,
        <kafai@...com>, <songliubraving@...com>, <yhs@...com>,
        <matthias.schiffer@...tq-group.com>, <info@...ux.net>,
        <gregkh@...uxfoundation.org>, <tglx@...utronix.de>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <zhe.he@...driver.com>
Subject: [PATCH] ARM: module: Avoid W and X mappings at the beginning

From: He Zhe <zhe.he@...driver.com>

It is more secure to map module memory as not-execute at the beginning.
Memory sections that need to be executable will be turned to executable
later in complete_formation.

This is a corresponding change for ARM to the following commit
commit f2c65fb3221a ("x86/modules: Avoid breaking W^X while loading modules")

Tested with test_bpf:
test_bpf: Summary: 378 PASSED, 0 FAILED, [0/366 JIT'ed]

Signed-off-by: He Zhe <zhe.he@...driver.com>
---
 arch/arm/kernel/module.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index deef17f..197b3b9 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -45,12 +45,12 @@ void *module_alloc(unsigned long size)
 		gfp_mask |= __GFP_NOWARN;
 
 	p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-				gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+				gfp_mask, PAGE_KERNEL, 0, NUMA_NO_NODE,
 				__builtin_return_address(0));
 	if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
 		return p;
 	return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
-				GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
 				__builtin_return_address(0));
 }
 #endif
-- 
2.7.4