[IMPROVE] safe read stack

Change-Id: Ia80787a2a0e6221ac887ec419535a19f28021491
Signed-off-by: Vyacheslav Cherkashin <v.cherkashin@samsung.com>

diff --git a/writer/kernel_operations.c b/writer/kernel_operations.c
index 76b1eca..d69fe74 100644 (file)
--- a/writer/kernel_operations.c
+++ b/writer/kernel_operations.c
@@ -24,6 +24,8 @@
  */
 
 #include <asm/ptrace.h>
+#include <asm/uaccess.h>
+#include <linux/kernel.h>
 
 #if defined(CONFIG_ARM)
 
@@ -49,8 +51,11 @@ int get_args(unsigned long args[], int cnt, struct pt_regs *regs)
 
        /* Get other args from stack */
        for (i = stack_args; i < cnt; ++i) {
-               unsigned long *args_in_sp = (unsigned long *)regs->ARM_sp;
-               args[i] = args_in_sp[i - stack_args];
+               unsigned long *args_in_sp = (unsigned long *)regs->ARM_sp +
+                                           i - stack_args;
+               if (get_user(args[i], args_in_sp))
+                       printk("failed to dereference a pointer, addr=%p\n",
+                              args_in_sp);
        }
 
        return 0;
@@ -88,8 +93,11 @@ int get_args(unsigned long args[], int cnt, struct pt_regs *regs)
 
        /* Get other args from stack */
        for (i = stack_args; i < cnt; ++i) {
-               unsigned long *args_in_sp = (unsigned long *)regs->sp + 1;
-               args[i] = args_in_sp[i - stack_args];
+               unsigned long *args_in_sp = (unsigned long *)regs->sp +
+                                           1 + i - stack_args;
+               if (get_user(args[i], args_in_sp))
+                       printk("failed to dereference a pointer, addr=%p\n",
+                              args_in_sp);
        }
 
        return 0;