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SubjectRe: [PATCH] block/compat_ioctl: fix range check in BLKGETSIZE
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On 4/8/22 16:47, Khazhismel Kumykov wrote:
> 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.
>
> Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
> ---
> block/ioctl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Noticed this one was sitting in my "not landed yet" pile, third time's
> the charm? :)
>
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 4a86340133e4..959e93a90b29 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -629,7 +629,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> return compat_put_long(argp,
> (bdev->bd_disk->bdi->ra_pages * PAGE_SIZE) / 512);
> case BLKGETSIZE:
> - if (bdev_nr_sectors(bdev) > ~0UL)
> + if (bdev_nr_sectors(bdev) > ~((compat_ulong_t)0UL))
> return -EFBIG;
> return compat_put_ulong(argp, bdev_nr_sectors(bdev));

A nit: the "UL" and two parentheses can be left out. Anyway:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

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