linux-kernel - Re: [PATCH V3] block: no show partitions if partno corrupted

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Message-ID: <2df5c0d7-cf9e-49ce-a39a-4e3d50c6df0c@kernel.dk>
Date: Tue, 14 Jan 2025 08:25:13 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Edward Adam Davis <eadavis@...com>
Cc: hare@...e.de, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 syzbot+fcee6b76cf2e261c51a4@...kaller.appspotmail.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH V3] block: no show partitions if partno corrupted

On 1/14/25 8:15 AM, Edward Adam Davis wrote:
> On Tue, 14 Jan 2025 08:02:15 -0700, Jens Axboe wrote:
>>> diff --git a/block/genhd.c b/block/genhd.c
>>> index 9130e163e191..3a9c36ad6bbd 100644
>>> --- a/block/genhd.c
>>> +++ b/block/genhd.c
>>> @@ -890,6 +890,9 @@ static int show_partition(struct seq_file *seqf, void *v)
>>>
>>>  	rcu_read_lock();
>>>  	xa_for_each(&sgp->part_tbl, idx, part) {
>>> +		int partno = bdev_partno(part);
>>> +
>>> +		WARN_ON_ONCE(partno >= DISK_MAX_PARTS);
>>>  		if (!bdev_nr_sectors(part))
>>>  			continue;
>>>  		seq_printf(seqf, "%4d  %7d %10llu %pg\n",
>>
>> Surely you still want to continue for that condition?
> No.

No?

> But like following, ok?
> diff --git a/block/genhd.c b/block/genhd.c
> index 9130e163e191..142b13620f0c 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -890,7 +890,10 @@ static int show_partition(struct seq_file *seqf, void *v)
>  
>         rcu_read_lock();
>         xa_for_each(&sgp->part_tbl, idx, part) {
> -               if (!bdev_nr_sectors(part))
> +               int partno = bdev_partno(part);
> +
> +               WARN_ON_ONCE(partno >= DISK_MAX_PARTS);
> +               if (!bdev_nr_sectors(part) || partno >= DISK_MAX_PARTS)
>                         continue;
>                 seq_printf(seqf, "%4d  %7d %10llu %pg\n",
>                            MAJOR(part->bd_dev), MINOR(part->bd_dev),

That's just silly...

	xa_for_each(&sgp->part_tbl, idx, part) {
		int partno = bdev_partno(part);

		if (!bdev_nr_sectors(part))
			continue;
		if (WARN_ON_ONCE(partno >= DISK_MAX_PARTS))
			continue;

		...
	}

-- 
Jens Axboe