devmem: add range_is_allowed() check to mmap of /dev/mem

Earlier patch that introduced CONFIG_NONPROMISC_DEVMEM, did the
range_is_allowed() check only for read and write. Add range_is_allowed()
check to mmap of /dev/mem as well.

Changes the paramaters of range_is_allowed() to pfn and size to handle
more than 32 bits of physical address on 32 bit arch cleanly.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 11 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index dcf6e31970a1..964ff3b1cff4 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -109,24 +109,26 @@ static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 #endif
 
 #ifdef CONFIG_NONPROMISC_DEVMEM
-static inline int range_is_allowed(unsigned long from, unsigned long to)
+static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
-        unsigned long cursor;
+        u64 from = ((u64)pfn) << PAGE_SHIFT;
+        u64 to = from + size;
+        u64 cursor = from;
 
-        cursor = from >> PAGE_SHIFT;
-        while ((cursor << PAGE_SHIFT) < to) {
-                if (!devmem_is_allowed(cursor)) {
-                        printk(KERN_INFO "Program %s tried to read /dev/mem "
-                                "between %lx->%lx.\n",
+        while (cursor < to) {
+                if (!devmem_is_allowed(pfn)) {
+                        printk(KERN_INFO
+                "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
                                 current->comm, from, to);
                         return 0;
                 }
-                cursor++;
+                cursor += PAGE_SIZE;
+                pfn++;
         }
         return 1;
 }
 #else
-static inline int range_is_allowed(unsigned long from, unsigned long to)
+static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
         return 1;
 }
@@ -181,7 +183,7 @@ static ssize_t read_mem(struct file * file, char __user * buf,
                  */
                 ptr = xlate_dev_mem_ptr(p);
 
-                if (!range_is_allowed(p, p+count))
+                if (!range_is_allowed(p >> PAGE_SHIFT, count))
                         return -EPERM;
                 if (copy_to_user(buf, ptr, sz))
                         return -EFAULT;
@@ -240,7 +242,7 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
                  */
                 ptr = xlate_dev_mem_ptr(p);
 
-                if (!range_is_allowed(p, p+sz))
+                if (!range_is_allowed(p >> PAGE_SHIFT, sz))
                         return -EPERM;
                 copied = copy_from_user(ptr, buf, sz);
                 if (copied) {
@@ -309,6 +311,9 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma)
         if (!private_mapping_ok(vma))
                 return -ENOSYS;
 
+        if (!range_is_allowed(vma->vm_pgoff, size))
+                return -EPERM;
+
         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
                                                  size,
                                                  vma->vm_page_prot);