Re: [PATCH 1/2] null_blk: return error for invalid zone size

From: Damien Le Moal <Damien.LeMoal@wdc.com>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [PATCH 1/2] null_blk: return error for invalid zone size
Date: Thu, 21 May 2020 02:19:03 +0000	[thread overview]
Message-ID: <BY5PR04MB69003201220D4DFADC4B0A12E7B70@BY5PR04MB6900.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20200520230152.36120-2-chaitanya.kulkarni@wdc.com

On 2020/05/21 8:02, Chaitanya Kulkarni wrote:
> In null_init_zone_dev() check if the zone size is larger than device
> capacity, return error if needed.
> 
> This also fixes the following oops :-
> 
> null_blk: changed the number of conventional zones to 4294967295
> BUG: kernel NULL pointer dereference, address: 0000000000000010
> PGD 7d76c5067 P4D 7d76c5067 PUD 7d240c067 PMD 0
> Oops: 0002 [#1] SMP NOPTI
> CPU: 4 PID: 5508 Comm: nullbtests.sh Tainted: G OE 5.7.0-rc4lblk-fnext0
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e4
> RIP: 0010:null_init_zoned_dev+0x17a/0x27f [null_blk]
> RSP: 0018:ffffc90007007e00 EFLAGS: 00010246
> RAX: 0000000000000020 RBX: ffff8887fb3f3c00 RCX: 0000000000000007
> RDX: 0000000000000000 RSI: ffff8887ca09d688 RDI: ffff888810fea510
> RBP: 0000000000000010 R08: ffff8887ca09d688 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff8887c26e8000
> R13: ffffffffa05e9390 R14: 0000000000000000 R15: 0000000000000001
> FS:  00007fcb5256f740(0000) GS:ffff888810e00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000010 CR3: 000000081e8fe000 CR4: 00000000003406e0
> Call Trace:
>  null_add_dev+0x534/0x71b [null_blk]
>  nullb_device_power_store.cold.41+0x8/0x2e [null_blk]
>  configfs_write_file+0xe6/0x150
>  vfs_write+0xba/0x1e0
>  ksys_write+0x5f/0xe0
>  do_syscall_64+0x60/0x250
>  entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x7fcb51c71840
> 
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

Looks good.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>

> ---
>  drivers/block/null_blk_zoned.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk_zoned.c
> index 9c19f747f394..cc47606d8ffe 100644
> --- a/drivers/block/null_blk_zoned.c
> +++ b/drivers/block/null_blk_zoned.c
> @@ -23,6 +23,10 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
>  		pr_err("zone_size must be power-of-two\n");
>  		return -EINVAL;
>  	}
> +	if (dev->zone_size > dev->size) {
> +		pr_err("Zone size larger than device capacity\n");
> +		return -EINVAL;
> +	}
>  
>  	dev->zone_size_sects = dev->zone_size << ZONE_SIZE_SHIFT;
>  	dev->nr_zones = dev_size >>
> 

-- 
Damien Le Moal
Western Digital Research