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authorPhilip Derrin <philip@cog.systems>2017-11-14 00:55:25 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-30 08:37:19 +0000
commit5f8046f7c9e3049000bbe610c15390bf698d681e (patch)
tree2c23cafc55056edd67d5d5033c18c0c18d1a09fc /arch/arm
parent29c4b6b4f46d4cc53b4f8c2b45e218ccfa1eea68 (diff)
downloadlinux-linaro-stable-5f8046f7c9e3049000bbe610c15390bf698d681e.tar.gz
ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE
commit 400eeffaffc7232c0ae1134fe04e14ae4fb48d8c upstream. Currently, for ARM kernels with CONFIG_ARM_LPAE and CONFIG_STRICT_KERNEL_RWX enabled, the 2MiB pages mapping the kernel code and rodata are writable. They are marked read-only in a software bit (L_PMD_SECT_RDONLY) but the hardware read-only bit is not set (PMD_SECT_AP2). For user mappings, the logic that propagates the software bit to the hardware bit is in set_pmd_at(); but for the kernel, section_update() writes the PMDs directly, skipping this logic. The fix is to set PMD_SECT_AP2 for read-only sections in section_update(), at the same time as L_PMD_SECT_RDONLY. Fixes: 1e3479225acb ("ARM: 8275/1: mm: fix PMD_SECT_RDONLY undeclared compile error") Signed-off-by: Philip Derrin <philip@cog.systems> Reported-by: Neil Dick <neil@cog.systems> Tested-by: Neil Dick <neil@cog.systems> Tested-by: Laura Abbott <labbott@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/init.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 7f8cd1b3557f..c29ad610311b 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -611,8 +611,8 @@ static struct section_perm ro_perms[] = {
.start = (unsigned long)_stext,
.end = (unsigned long)__init_begin,
#ifdef CONFIG_ARM_LPAE
- .mask = ~L_PMD_SECT_RDONLY,
- .prot = L_PMD_SECT_RDONLY,
+ .mask = ~(L_PMD_SECT_RDONLY | PMD_SECT_AP2),
+ .prot = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
#else
.mask = ~(PMD_SECT_APX | PMD_SECT_AP_WRITE),
.prot = PMD_SECT_APX | PMD_SECT_AP_WRITE,