Messages in this thread | | | Subject | Re: [PATCH -next] fs: sysv: check sbi->s_firstdatazone in complete_read_super | From | Liu Shixin <> | Date | Thu, 31 Mar 2022 11:49:08 +0800 |
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The type I used is sysv v7.
I discovered this problem through a syzkaller use case. The use case first create a file via memfd and bind it to loop0. Then mount it to a folder with type v7. No error is reported for preceding operations. Finally when create a file, the warning in inc_nlink is triggered. I want to look the filesystem information, so I execute 'df' command and find this problem.
Btw, I think the warning may be a follow-up problem caused by the filesystem being created or mounted incorrectly.
Thanks,
On 2022/3/30 23:42, Christoph Hellwig wrote: > On Wed, Mar 30, 2022 at 06:42:15PM +0800, Liu Shixin wrote: >> sbi->s_firstinodezone is initialized to 2 and sbi->s_firstdatazone is read >> from sbd. There's no guarantee that sbi->s_firstdatazone must bigger than >> sbi->s_firstinodezone. If sbi->s_firstdatazone less than 2, the filesystem >> can still be mounted unexpetly. At this point, sbi->s_ninodes flip to very >> large value and this filesystem is broken. We can observe this by >> executing 'df' command. When we execute, we will get an error message: >> "sysv_count_free_inodes: unable to read inode table" > This looks fine. Just curious: which variant of the sysv fs do you > use and what is the use case? > . >
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