Re: [PATCH] fs/ntfs: fix BUG_ON of ntfs_read_block()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 23, 2022 at 03:51:31AM +0000, cgel.zte@gmail.com wrote:
> From: xu xin <xu.xin16@zte.com.cn>
> 
> As the bug description, attckers can use this bug to crash the system
> When CONFIG_NTFS_FS is set.
> 
> So remove the BUG_ON, and use WARN and return instead until someone
> really solve the bug.
> 
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Reported-by: syzbot+6a5a7672f663cce8b156@syzkaller.appspotmail.com
> Reviewed-by: Songyi Zhang <zhang.songyi@zte.com.cn>
> Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
> Reviewed-by: Jiang Xuexin<jiang.xuexin@zte.com.cn>
> Reviewed-by: Zhang wenya<zhang.wenya1@zte.com.cn>
> Signed-off-by: xu xin <xu.xin16@zte.com.cn>
> ---
>  fs/ntfs/aops.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
> index 5f4fb6ca6f2e..b6fd7e711420 100644
> --- a/fs/ntfs/aops.c
> +++ b/fs/ntfs/aops.c
> @@ -183,7 +183,11 @@ static int ntfs_read_block(struct page *page)
>  	vol = ni->vol;
>  
>  	/* $MFT/$DATA must have its complete runlist in memory at all times. */
> -	BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
> +	if (unlikely(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni))) {
> +		WARN(1, "NTFS: ni->runlist.rl, ni->mft_no, and NInoAttr(ni) is null!\n");

So for systems with panic-on-warn, you are still crashing?  Why is this
WARN() line still needed here?

thanks,

greg k-h