i2c-dev: Use memdup_user

Use memdup_user when user data is immediately copied into the allocated
region.  Note that in the second case, the ++i is no longer necessary, as
the last value is already freed if needed by the call to memdup_user.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression from,to,size,flag;
position p;
identifier l1,l2;
@@

-  to = \(kmalloc@p\|kzalloc@p\)(size,flag);
+  to = memdup_user(from,size);
   if (
-      to==NULL
+      IS_ERR(to)
                 || ...) {
   <+... when != goto l1;
-  -ENOMEM
+  PTR_ERR(to)
   ...+>
   }
-  if (copy_from_user(to, from, size) != 0) {
-    <+... when != goto l2;
-    -EFAULT
-    ...+>
-  }
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index b3fcb59..0b0427f 100644 (file)
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -167,13 +167,9 @@ static ssize_t i2cdev_write(struct file *file, const char __user *buf,
        if (count > 8192)
                count = 8192;
 
-       tmp = kmalloc(count, GFP_KERNEL);
-       if (tmp == NULL)
-               return -ENOMEM;
-       if (copy_from_user(tmp, buf, count)) {
-               kfree(tmp);
-               return -EFAULT;
-       }
+       tmp = memdup_user(buf, count);
+       if (IS_ERR(tmp))
+               return PTR_ERR(tmp);
 
        pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
                iminor(file->f_path.dentry->d_inode), count);
@@ -245,15 +241,9 @@ static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
                        break;
                }
                data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
-               rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
-               if (rdwr_pa[i].buf == NULL) {
-                       res = -ENOMEM;
-                       break;
-               }
-               if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i],
-                                  rdwr_pa[i].len)) {
-                               ++i; /* Needs to be kfreed too */
-                               res = -EFAULT;
+               rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
+               if (IS_ERR(rdwr_pa[i].buf)) {
+                       res = PTR_ERR(rdwr_pa[i].buf);
                        break;
                }
        }