[PATCH v5.10] block/compat_ioctl: fix range check in BLKGETSIZE

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[ Upstream commit ccf16413e520164eb718cf8b22a30438da80ff23 ]

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@xxxxxxx>
Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220414224056.2875681-1-khazhy@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 block/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index ed240e170e14..e7eed7dadb5c 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -679,7 +679,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 			       (bdev->bd_bdi->ra_pages * PAGE_SIZE) / 512);
 	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(argp, size >> 9);
 
-- 
2.36.0.rc2.479.g8af0fa9b8e-goog




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