RE: [PATCH v2] nfp: fix use-after-free in area_cache_get()

[Yinjun Zhang]

On Wed, 10 Aug 2022 12:04:45 +0800 Jialiang Wang wrote:
> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
> b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
> index 34c0d2ddf9ef..a83b8ee49062 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
> +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
> @@ -873,10 +873,6 @@ area_cache_get(struct nfp_cpp *cpp, u32 id,
>  		cache->addr = 0;
>  	}
> 
> -	/* Adjust the start address to be cache size aligned */
> -	cache->id = id;
> -	cache->addr = addr & ~(u64)(cache->size - 1);
> -
>  	/* Re-init to the new ID and address */
>  	if (cpp->op->area_init) {
>  		err = cpp->op->area_init(cache->area,
> @@ -894,6 +890,10 @@ area_cache_get(struct nfp_cpp *cpp, u32 id,
>  		return NULL;
>  	}
> 
> +	/* Adjust the start address to be cache size aligned */
> +	cache->id = id;
> +	cache->addr = addr & ~(u64)(cache->size - 1);

`cache->addr` is used in `area_init`, so it should be set in advance.

> +
>  exit:
>  	/* Adjust offset */
>  	*offset = addr - cache->addr;
> --
> 2.17.1