[ARM] 4839/1: fixes kernel Oops in /dev/mem device driver for memory map with PHYS_OFF

"cat /dev/mem" may cause kernel Oops for boards with PHYS_OFFSET != 0
because character device is mapped to addresses starting from zero
and there is no protection against such situation.
Patch just add this.

Signed-off-by: Alexandre Rusev <arusev@ru.mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 2728b0e7d2bb..3f6dc40b8353 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -120,6 +120,8 @@ full_search:
  */
 int valid_phys_addr_range(unsigned long addr, size_t size)
 {
+        if (addr < PHYS_OFFSET)
+                return 0;
         if (addr + size > __pa(high_memory))
                 return 0;