Re: [XEN][PATCH v10 02/20] common/device_tree.c: unflatten_device_tree() propagate errors

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 25 Aug 2023, Vikram Garhwal wrote:
> This will be useful in dynamic node programming when new dt nodes are 
> unflattend
> during runtime. Invalid device tree node related errors should be propagated
> back to the caller.
> 
> Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes from v9:
>     Replace __be64 with void.
> Changes from v7:
>     Free allocated memory in case of errors when calling unflatten_dt_node.
> ---
> ---
>  xen/common/device_tree.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 7c6b41c3b4..b6d9f018c6 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -2110,6 +2110,9 @@ static int __init __unflatten_device_tree(const void 
> *fdt,
>      /* First pass, scan for size */
>      start = ((unsigned long)fdt) + fdt_off_dt_struct(fdt);
>      size = unflatten_dt_node(fdt, 0, &start, NULL, NULL, 0);
> +    if ( !size )
> +        return -EINVAL;
> +
>      size = (size | 3) + 1;
>  
>      dt_dprintk("  size is %#lx allocating...\n", size);
> @@ -2127,11 +2130,21 @@ static int __init __unflatten_device_tree(const void 
> *fdt,
>      start = ((unsigned long)fdt) + fdt_off_dt_struct(fdt);
>      unflatten_dt_node(fdt, mem, &start, NULL, &allnextp, 0);
>      if ( be32_to_cpup((__be32 *)start) != FDT_END )
> -        printk(XENLOG_WARNING "Weird tag at end of tree: %08x\n",
> +    {
> +        printk(XENLOG_ERR "Weird tag at end of tree: %08x\n",
>                    *((u32 *)start));
> +        xfree((void *)mem);
> +        return -EINVAL;
> +    }
> +
>      if ( be32_to_cpu(((__be32 *)mem)[size / 4]) != 0xdeadbeefU )
> -        printk(XENLOG_WARNING "End of tree marker overwritten: %08x\n",
> +    {
> +        printk(XENLOG_ERR "End of tree marker overwritten: %08x\n",
>                    be32_to_cpu(((__be32 *)mem)[size / 4]));
> +        xfree((void *)mem);
> +        return -EINVAL;
> +    }
> +
>      *allnextp = NULL;
>  
>      dt_dprintk(" <- unflatten_device_tree()\n");
> -- 
> 2.17.1
>