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authorPhilip Derrin <philip@cog.systems>2017-11-14 00:55:25 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2017-11-21 15:10:07 +0000
commit400eeffaffc7232c0ae1134fe04e14ae4fb48d8c (patch)
treea21d5b4f3044abb133eeb03cb12db8664b964abd
parent3b0c0c922ff4be275a8beb87ce5657d16f355b54 (diff)
ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE
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> Cc: stable@vger.kernel.org Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
-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 ad80548325fe..0f6d1537f330 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -639,8 +639,8 @@ 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,