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>

1 files changed, 6 insertions, 16 deletions

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index b3fcb59a5a10..0b0427f7d348 100644
--- 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;
                 }
         }