[ARM] 3813/1: prevent >= 4G /dev/mem mmap()
Prevent userland from mapping in physical address regions >= 4G by
checking for that in valid_mmap_phys_addr_range().
Unfortunately, we cannot override valid_mmap_phys_addr_range() without
also overriding valid_phys_addr_range(), so copy drivers/char/mem.c's
version of valid_phys_addr_range() over to arch/arm/mm/mmap.c as well.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 29e5480..b0b5f46 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -114,3 +114,25 @@
}
}
+
+/*
+ * You really shouldn't be using read() or write() on /dev/mem. This
+ * might go away in the future.
+ */
+int valid_phys_addr_range(unsigned long addr, size_t size)
+{
+ if (addr + size > __pa(high_memory))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * We don't use supersection mappings for mmap() on /dev/mem, which
+ * means that we can't map the memory area above the 4G barrier into
+ * userspace.
+ */
+int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
+{
+ return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
+}