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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>,
        Khazhismel Kumykov <khazhy@google.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 4.9 24/24] block/compat_ioctl: fix range check in BLKGETSIZE
Date:   Tue, 26 Apr 2022 10:21:18 +0200
Message-Id: <20220426081732.085252639@linuxfoundation.org>
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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
@@ -394,7 +394,7 @@ 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);