Several potential vulnerabilities in the filesystem

[Gao Xiang]

Hi Jianqiang,

On 2024/6/5 19:00, jianqiang wang wrote:
> Hi,
> 
> I do have the crafted image.
> 
> payload_00500, payload_00763, payload_00846 can be used to reproduce
> 1,2,3 vulnerabilities respectively.
> 
> Each image is a hard drive file and the vulnerabilities can be
> triggered by performing the following operations:
> 
>      struct udevice *dev;
>      uclass_first_device_err(UCLASS_IDE, &dev);  //detect the block device
> 
>      fs_set_blk_dev("ide","0:1", 0);
>      fs_ls("/");   //mount the first partition and list the root directory files
> 
>      fs_set_blk_dev("ide","0:1", 0);
>      char buf[10];
>      buf[0] = 0;
>      buf[1] = 0;
>      buf[2] = 0;
>      buf[3] = 0;
>      loff_t actread = 0;
>      fs_read("/a.txt", (ulong)buf, 0, 5, &actread);
>      printf("fd actread %lld %x %x %x\n",actread,buf[0],buf[1],buf[2]);
>   read the /a.txt file
> 
> 
>      fs_set_blk_dev("ide","0:1", 0);
>      fs_read("/a.txt.ln", (ulong)buf, 0, 5, &actread);
>      printf("fd actread %lld %x %x %x\n",actread,buf[0],buf[1],buf[2]);
>   read the /a.txt.ln symbol file
> 
>      fs_set_blk_dev("ide","0:1", 0);
>      fs_unlink("/a.txt.ln");  //unlink it
> 
> The second and third may not trigger a crash however, can be observed
> by inserting logging before the memset/memcpy function.

Sorry, I just found that this issue was already fixed in erofs-utils:
https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/commit/?id=884866ca07817e97c59605a2fa858a0b732d3f3c

Would you mind checking if the patch above fixes the issue?

Hi Jianan,
Would you mind backporting this patch for u-boot?

Thanks,
Gao Xiang

> 
> Best regards
> 
> Gao Xiang <hsiangkao at linux.alibaba.com> 于2024年6月5日周三 05:10写道：
>>
>>
>>
>> On 2024/6/5 06:53, jianqiang wang wrote:
>>> Hi Das U-Boot developers,
>>>
>>
>> ...
>>
>>>
>>> 2. in file fs/erofs/data.c, function z_erofs_read_one_data, the node
>>> data is read from the storage, however, without a proper check, the
>>> data can be corrupted. For example, the inode data is used in function
>>> z_erofs_read_data, map.m_llen will be calculated to a very large
>>> value, which means the length variable will be very large. It will
>>> cause a large memory clear with memset(buffer + end - offset, 0,
>>> length);
>>
>> Would you mind giving a reproducer or a crafted image to trigger
>> this?  Or it's your pure observation.
>>
>> Thanks,
>> Gao XIang
>>