Re: [PATCH v4 08/10] loop: Rework lo_ioctl() __user argument casting

[Christoph Hellwig]

On Wed, Apr 29, 2020 at 04:03:39PM +0200, Martijn Coenen wrote:
> In preparation for a new ioctl that needs to copy_from_user(); makes the
> code easier to read as well.
> 
> Signed-off-by: Martijn Coenen 

Looks good,

Reviewed-by: Christoph Hellwig 

Btw, it seems like you have dropped all the reviews from the previous
versions, even if nothing substantial changed.  Please keep them unless
a patch actually is reworked.

[PATCH v4 08/10] loop: Rework lo_ioctl() __user argument casting

[Martijn Coenen]

In preparation for a new ioctl that needs to copy_from_user(); makes the
code easier to read as well.

Signed-off-by: Martijn Coenen 
---
 drivers/block/loop.c | 11 +--
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 60ba1ed95d77..f172a64333aa 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1659,6 +1659,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t 
mode,
unsigned int cmd, unsigned long arg)
 {
struct loop_device *lo = bdev->bd_disk->private_data;
+   void __user *argp = (void __user *) arg;
int err;
 
switch (cmd) {
@@ -1671,21 +1672,19 @@ static int lo_ioctl(struct block_device *bdev, fmode_t 
mode,
case LOOP_SET_STATUS:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-   err = loop_set_status_old(lo,
-   (struct loop_info __user *)arg);
+   err = loop_set_status_old(lo, argp);
}
break;
case LOOP_GET_STATUS:
-   return loop_get_status_old(lo, (struct loop_info __user *) arg);
+   return loop_get_status_old(lo, argp);
case LOOP_SET_STATUS64:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-   err = loop_set_status64(lo,
-   (struct loop_info64 __user *) arg);
+   err = loop_set_status64(lo, argp);
}
break;
case LOOP_GET_STATUS64:
-   return loop_get_status64(lo, (struct loop_info64 __user *) arg);
+   return loop_get_status64(lo, argp);
case LOOP_SET_CAPACITY:
case LOOP_SET_DIRECT_IO:
case LOOP_SET_BLOCK_SIZE:
-- 
2.26.2.303.gf8c07b1a785-goog