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Subject[PATCH v3] ARM: mm: fix reporting of read-only PMD bits
On non-LPAE ARMv6+, read-only PMD bits are defined with the combination
"PMD_SECT_APX | PMD_SECT_AP_WRITE". Adjusted the bit masks to correctly
report this.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
v3:
- check for pre-v6 CPUs on the page table report.
v2:
- reorder bits, suggested by Olof.
---
arch/arm/mm/dump.c | 31 +++++++++++++++++++++++++------
1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index ef69152f9b52..c1122d266c45 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -121,23 +121,42 @@ static const struct prot_bits pte_bits[] = {

static const struct prot_bits section_bits[] = {
#ifndef CONFIG_ARM_LPAE
- /* These are approximate */
+# if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_V6K) || defined(CONFIG_CPU_V7)
{
- .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
- .val = 0,
+ .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .val = PMD_SECT_APX | PMD_SECT_AP_WRITE,
.set = " ro",
}, {
- .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_WRITE,
.set = " RW",
}, {
- .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ,
.set = "USR ro",
}, {
- .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.set = "USR RW",
+# else
+ /* These are approximate */
+ {
+ .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .val = 0,
+ .set = " ro",
+ }, {
+ .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .val = PMD_SECT_AP_WRITE,
+ .set = " RW",
+ }, {
+ .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .val = PMD_SECT_AP_READ,
+ .set = "USR ro",
+ }, {
+ .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
+ .set = "USR RW",
+# endif
#else
{
.mask = PMD_SECT_USER,
--
1.7.9.5

--
Kees Cook
Chrome OS Security


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