Re: [PATCH] btrfs: Check superblock csum type to avoid 0 division or array overflow.

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message  --------
Subject: Re: [PATCH] btrfs: Check superblock csum type to avoid 0 
division or array overflow.
From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2015年04月24日 00:16

> On Thu, Apr 23, 2015 at 09:31:21AM +0800, Qu Wenruo wrote:
>> Current btrfs only support CRC32 checksum, and if csum_type is 1, we
>> will get 0 csum size, causing 0 division later destroy the whole kernel.
>> Or csum_type is later than 1, we will get data from other random memory
>> causing more problem.
>
> The check for csum type is already there in btrfs_check_super_csum, but
> it's wrong and should be fixed.
>
> btrfs_csum_sizes = { 4, 0 };
>
>   429         if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
>   430                 printk(KERN_ERR "BTRFS: unsupported checksum algorithm %u\n",
>   431                                 csum_type);
>   432                 ret = 1;
>   433         }
>   434
>
> and the check fails to catch csum_type == 1.
>
Thanks for pointing the existing codes, I'll update the patch.

Thanks,
Qu