ARM: 6955/1: cmpxchg syscall should data abort if page not write
If the page to cmpxchg is user mode read only (not write),
we should simulate a data abort first.
Signed-off-by: Po-Yu Chuang <ratbert@faraday-tech.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index d52eec2..c5ead3c 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -563,7 +563,7 @@
if (!pmd_present(*pmd))
goto bad_access;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
- if (!pte_present(*pte) || !pte_dirty(*pte)) {
+ if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
pte_unmap_unlock(pte, ptl);
goto bad_access;
}