Re: [PATCH] erofs: fix the unmapped access in z_erofs_fill_inode_lazy()

[Gao Xiang]

On Tue, Oct 04, 2022 at 10:49:51PM +0800, Yue Hu wrote:
> From: Yue Hu <huyue2@xxxxxxxxxxx>
> 
> Note that we are still accessing 'h_idata_size' and 'h_fragmentoff'
> after calling erofs_put_metabuf(), that is not correct. Fix it.
> 
> Fixes: ab92184ff8f1 ("add on-disk compressed tail-packing inline support")
> Fixes: b15b2e307c3a ("support on-disk compressed fragments data")
> Signed-off-by: Yue Hu <huyue2@xxxxxxxxxxx>
> ---
>  fs/erofs/zmap.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 

erofs: fix invalid unmapped accesses in z_erofs_fill_inode_lazy()

> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
> index 44c27ef39c43..1a15bbf18ba3 100644
> --- a/fs/erofs/zmap.c
> +++ b/fs/erofs/zmap.c
> @@ -58,7 +58,7 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
>  	pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
>  		    vi->xattr_isize, 8);
>  	kaddr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos),
> -				   EROFS_KMAP_ATOMIC);
> +				   EROFS_KMAP);

	kaddr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos), EROFS_KMAP); ?

Also I will use kmap_local later to replace kmap and kmap_atomic if
possible.

>  	if (IS_ERR(kaddr)) {
>  		err = PTR_ERR(kaddr);
>  		goto out_unlock;
> @@ -73,7 +73,7 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
>  		vi->z_advise = Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
>  		vi->z_fragmentoff = le64_to_cpu(*(__le64 *)h) ^ (1ULL << 63);
>  		vi->z_tailextent_headlcn = 0;
> -		goto unmap_done;
> +		goto init_done;
>  	}
>  	vi->z_advise = le16_to_cpu(h->h_advise);
>  	vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
> @@ -105,10 +105,6 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
>  		err = -EFSCORRUPTED;
>  		goto unmap_done;
>  	}
> -unmap_done:
> -	erofs_put_metabuf(&buf);
> -	if (err)
> -		goto out_unlock;
>  
>  	if (vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER) {
>  		struct erofs_map_blocks map = {
> @@ -127,7 +123,7 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
>  			err = -EFSCORRUPTED;
>  		}
>  		if (err < 0)
> -			goto out_unlock;
> +			goto unmap_done;
>  	}
>  
>  	if (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER &&
> @@ -141,11 +137,14 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
>  					    EROFS_GET_BLOCKS_FINDTAIL);
>  		erofs_put_metabuf(&map.buf);
>  		if (err < 0)
> -			goto out_unlock;
> +			goto unmap_done;
>  	}
> +init_done:

done:

>  	/* paired with smp_mb() at the beginning of the function */
>  	smp_mb();
>  	set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
> +unmap_done:

out_put_metabuf:

Thanks,
Gao Xiang

> +	erofs_put_metabuf(&buf);
>  out_unlock:
>  	clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
>  	return err;
> -- 
> 2.25.1
>