diff mbox series

[v3,1/9] loop: Factor out loop size validation

Message ID 20200427074222.65369-2-maco@android.com (mailing list archive)
State New, archived
Headers show
Series Add a new LOOP_SET_FD_AND_STATUS ioctl | expand

Commit Message

Martijn Coenen April 27, 2020, 7:42 a.m. UTC 
Ensuring we don't truncate loff_t when casting to sector_t is done in
multiple places; factor it out.

Signed-off-by: Martijn Coenen <maco@android.com>
---
 drivers/block/loop.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

Comments

Christoph Hellwig April 27, 2020, 2:53 p.m. UTC | #1 
> +static int
> +loop_validate_size(loff_t size)
> +{
> +	if ((loff_t)(sector_t)size != size)
> +		return -EFBIG;
> +	else
> +		return 0;

Nit: no real need for an else after a return.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f1754262fc94..f812f11649d3 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -228,15 +228,30 @@  static void __loop_update_dio(struct loop_device *lo, bool dio)
 		blk_mq_unfreeze_queue(lo->lo_queue);
 }
 
+/**
+ * loop_validate_size() - validates that the passed in size fits in a sector_t
+ * @size: size to validate
+ */
+static int
+loop_validate_size(loff_t size)
+{
+	if ((loff_t)(sector_t)size != size)
+		return -EFBIG;
+	else
+		return 0;
+}
+
 static int
 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
 {
+	int err;
 	loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
-	sector_t x = (sector_t)size;
 	struct block_device *bdev = lo->lo_device;
 
-	if (unlikely((loff_t)x != size))
-		return -EFBIG;
+	err = loop_validate_size(size);
+	if (err)
+		return err;
+
 	if (lo->lo_offset != offset)
 		lo->lo_offset = offset;
 	if (lo->lo_sizelimit != sizelimit)
@@ -1003,9 +1018,9 @@  static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	    !file->f_op->write_iter)
 		lo_flags |= LO_FLAGS_READ_ONLY;
 
-	error = -EFBIG;
 	size = get_loop_size(lo, file);
-	if ((loff_t)(sector_t)size != size)
+	error = loop_validate_size(size);
+	if (error)
 		goto out_unlock;
 	error = loop_prepare_queue(lo);
 	if (error)