Re: [PATCH 2/2] ocfs2: validate DIO orphan slot during inode read

[Joseph Qi]

On 8/3/26 11:00 AM, ZhengYuan Huang wrote:
> [BUG]
> A corrupted append-DIO dinode (high byte at offset 0xa1 
> corrupted from 0 to 1) can carry an i_dio_orphaned_slot
> outside the mounted filesystem slot range and trigger a 
> use-after-free error:
> 
> BUG: KASAN: slab-use-after-free in ocfs2_get_system_file_inode+0x780/0x820 fs/ocfs2/sysfile.c:102
> Read of size 8 at addr ffff88800b767c00 by task kworker/u8:3/85
> Call Trace:
>  ...
>  ocfs2_get_system_file_inode+0x780/0x820 fs/ocfs2/sysfile.c:102
>  ocfs2_wipe_inode+0x292/0xf70 fs/ocfs2/inode.c:840
>  ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
>  ocfs2_evict_inode+0x6c9/0x1170 fs/ocfs2/inode.c:1295
>  evict+0x38e/0x8f0 fs/inode.c:810
>  iput_final fs/inode.c:1914 [inline]
>  iput fs/inode.c:1966 [inline]
>  iput+0x55b/0x8b0 fs/inode.c:1926
>  ocfs2_recover_orphans+0x610/0xe40 fs/ocfs2/journal.c:2374
>  ocfs2_complete_recovery+0x5af/0xd00 fs/ocfs2/journal.c:1373
>  ...
> 
> [CAUSE]
> ocfs2_del_inode_from_orphan() uses i_dio_orphaned_slot to index the
> slot-local system inode cache. The dinode validator does not check
> this active slot, so an out-of-range value produces an invalid cache
> entry pointer that is dereferenced as an inode pointer.
> 
> [FIX]
> Reject an active i_dio_orphaned_slot outside the slot range during
> dinode validation, before DIO orphan recovery can consume it.
> 
> Fixes: 06ee5c75b575 ("ocfs2: add functions to add and remove inode in orphan dir")
> Signed-off-by: ZhengYuan Huang <gality369@xxxxxxxxx>

Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
> ---
>  fs/ocfs2/inode.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
> index 358ab3535366..180107a11046 100644
> --- a/fs/ocfs2/inode.c
> +++ b/fs/ocfs2/inode.c
> @@ -1536,6 +1536,14 @@ int ocfs2_validate_inode_block(struct super_block *sb,
>  		goto bail;
>  	}
>  
> +	if ((le32_to_cpu(di->i_flags) & OCFS2_DIO_ORPHANED_FL) &&
> +	    le16_to_cpu(di->i_dio_orphaned_slot) >= OCFS2_SB(sb)->max_slots) {
> +		rc = ocfs2_error(sb, "Invalid dinode %llu: DIO orphaned slot %u\n",
> +				 (unsigned long long)bh->b_blocknr,
> +				 le16_to_cpu(di->i_dio_orphaned_slot));
> +		goto bail;
> +	}
> +
>  	/*
>  	 * Reject dinodes whose i_mode does not name one of the seven
>  	 * canonical POSIX file types.  ocfs2_populate_inode() copies