[PATCH 1/2] mmc-block: Use memdup_user() rather than duplicating its implementation

[SF Markus Elfring]

From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Fri, 19 Aug 2016 22:46:38 +0200

* Reuse existing functionality from memdup_user() instead of keeping
  duplicate source code.

  This issue was detected by using the Coccinelle software.

* Delete the integer variable "err" then because the pointer
  variable "idata" should be sufficient to handle return values alone
  in this function.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 drivers/mmc/card/block.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 48a5dd7..6ce9492 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -337,22 +337,21 @@ static struct mmc_blk_ioc_data 
*mmc_blk_ioctl_copy_from_user(
        struct mmc_ioc_cmd __user *user)
 {
        struct mmc_blk_ioc_data *idata;
-       int err;
 
        idata = kmalloc(sizeof(*idata), GFP_KERNEL);
        if (!idata) {
-               err = -ENOMEM;
+               idata = ERR_PTR(-ENOMEM);
                goto out;
        }
 
        if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
-               err = -EFAULT;
+               idata = ERR_PTR(-EFAULT);
                goto idata_err;
        }
 
        idata->buf_bytes = (u64) idata->ic.blksz * idata->ic.blocks;
        if (idata->buf_bytes > MMC_IOC_MAX_BYTES) {
-               err = -EOVERFLOW;
+               idata = ERR_PTR(-EOVERFLOW);
                goto idata_err;
        }
 
@@ -361,26 +360,19 @@ static struct mmc_blk_ioc_data 
*mmc_blk_ioctl_copy_from_user(
                return idata;
        }
 
-       idata->buf = kmalloc(idata->buf_bytes, GFP_KERNEL);
-       if (!idata->buf) {
-               err = -ENOMEM;
+       idata->buf = memdup_user((void __user *)(unsigned long)
+                                idata->ic.data_ptr,
+                                idata->buf_bytes);
+       if (IS_ERR(idata->buf)) {
+               idata = (void *) idata->buf;
                goto idata_err;
        }
-
-       if (copy_from_user(idata->buf, (void __user *)(unsigned long)
-                                       idata->ic.data_ptr, idata->buf_bytes)) {
-               err = -EFAULT;
-               goto copy_err;
-       }
-
        return idata;
 
-copy_err:
-       kfree(idata->buf);
 idata_err:
        kfree(idata);
 out:
-       return ERR_PTR(err);
+       return idata;
 }
 
 static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr,
-- 
2.9.3