[PATCH 5.4 61/62] block/compat_ioctl: fix range check in BLKGETSIZE

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Khazhismel Kumykov <khazhy@google.com>

commit ccf16413e520164eb718cf8b22a30438da80ff23 upstream.

kernel ulong and compat_ulong_t may not be same width. Use type directly
to eliminate mismatches.

This would result in truncation rather than EFBIG for 32bit mode for
large disks.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220414224056.2875681-1-khazhy@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 block/compat_ioctl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -393,7 +393,7 @@ long compat_blkdev_ioctl(struct file *fi
 		return 0;
 	case BLKGETSIZE:
 		size = i_size_read(bdev->bd_inode);
-		if ((size >> 9) > ~0UL)
+		if ((size >> 9) > ~(compat_ulong_t)0)
 			return -EFBIG;
 		return compat_put_ulong(arg, size >> 9);