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authorPhilip Derrin <philip@cog.systems>2017-11-14 00:55:26 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2017-11-21 15:10:07 +0000
commit3b0c0c922ff4be275a8beb87ce5657d16f355b54 (patch)
treec12be9315a645c400e1e62b91158237be85eb6d0
parent29337b60ab5d2a499847c26d45e3cb81f62c2f26 (diff)
ARM: 8721/1: mm: dump: check hardware RO bit for LPAE
When CONFIG_ARM_LPAE is set, the PMD dump relies on the software read-only bit to determine whether a page is writable. This concealed a bug which left the kernel text section writable (AP2=0) while marked read-only in the software bit. In a kernel with the AP2 bug, the dump looks like this: ---[ Kernel Mapping ]--- 0xc0000000-0xc0200000 2M RW NX SHD 0xc0200000-0xc0600000 4M ro x SHD 0xc0600000-0xc0800000 2M ro NX SHD 0xc0800000-0xc4800000 64M RW NX SHD The fix is to check that the software and hardware bits are both set before displaying "ro". The dump then shows the true perms: ---[ Kernel Mapping ]--- 0xc0000000-0xc0200000 2M RW NX SHD 0xc0200000-0xc0600000 4M RW x SHD 0xc0600000-0xc0800000 2M RW NX SHD 0xc0800000-0xc4800000 64M RW NX SHD Fixes: ded947798469 ("ARM: 8109/1: mm: Modify pte_write and pmd_write logic for LPAE") Signed-off-by: Philip Derrin <philip@cog.systems> Tested-by: Neil Dick <neil@cog.systems> 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/dump.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index 35ff45470dbf..fc3b44028cfb 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -129,8 +129,8 @@ static const struct prot_bits section_bits[] = {
.val = PMD_SECT_USER,
.set = "USR",
}, {
- .mask = L_PMD_SECT_RDONLY,
- .val = L_PMD_SECT_RDONLY,
+ .mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
+ .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
.set = "ro",
.clear = "RW",
#elif __LINUX_ARM_ARCH__ >= 6