Re: [PATCH V2] jfs: add sanity check for agwidth in dbMount

[Dave Kleikamp <dave.kleikamp@oracle.com>]

On 2/20/25 5:24AM, Edward Adam Davis wrote:
> The width in dmapctl of the AG is zero, it trigger a divide error when
> calculating the control page level in dbAllocAG.
> 
> To avoid this issue, add a check for agwidth in dbAllocAG.

Looks good. Will add this to jfs-next.

Thanks,
Shaggy

> 
> Reported-and-tested-by: syzbot+7c808908291a569281a9@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
> V1 -> V2: move the check to dbMount
> 
>   fs/jfs/jfs_dmap.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index f9009e4f9ffd..62f55e7ed840 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -204,6 +204,10 @@ int dbMount(struct inode *ipbmap)
>   	bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
>   	bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
>   	bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
> +	if (!bmp->db_agwidth) {
> +		err = -EINVAL;
> +		goto err_release_metapage;
> +	}
>   	bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
>   	bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
>   	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||