linux-hardening - Re: [PATCH v3 1/3] net: mana: Add flex array to struct mana_cfg_rx_steer_req

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Date: Mon, 8 Apr 2024 21:34:59 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Erick Archer <erick.archer@...look.com>
Cc: Long Li <longli@...rosoft.com>, Ajay Sharma <sharmaajay@...rosoft.com>, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, 
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Kees Cook <keescook@...omium.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Bill Wendling <morbo@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>, 
	Leon Romanovsky <leon@...nel.org>, Shradha Gupta <shradhagupta@...ux.microsoft.com>, 
	Konstantin Taranov <kotaranov@...rosoft.com>, linux-rdma@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH v3 1/3] net: mana: Add flex array to struct
 mana_cfg_rx_steer_req_v2

Hi,

On Sat, Apr 06, 2024 at 04:23:35PM +0200, Erick Archer wrote:
> The "struct mana_cfg_rx_steer_req_v2" uses a dynamically sized set of
> trailing elements. Specifically, it uses a "mana_handle_t" array. So,
> use the preferred way in the kernel declaring a flexible array [1].
> 
> At the same time, prepare for the coming implementation by GCC and Clang
> of the __counted_by attribute. Flexible array members annotated with
> __counted_by can have their accesses bounds-checked at run-time via
> CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for
> strcpy/memcpy-family functions).
> 
> This is a previous step to refactor the two consumers of this structure.
> 
>  drivers/infiniband/hw/mana/qp.c
>  drivers/net/ethernet/microsoft/mana/mana_en.c
> 
> The ultimate goal is to avoid the open-coded arithmetic in the memory
> allocator functions [2] using the "struct_size" macro.
> 
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#zero-length-and-one-element-arrays [1]
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [2]
> Signed-off-by: Erick Archer <erick.archer@...look.com>

I think this could have all been one patch, I found myself jumping
around the three patches here piecing together context.

Reviewed-by: Justin Stitt <justinstitt@...gle.com>

> ---
>  include/net/mana/mana.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
> index 4eeedf14711b..561f6719fb4e 100644
> --- a/include/net/mana/mana.h
> +++ b/include/net/mana/mana.h
> @@ -670,6 +670,7 @@ struct mana_cfg_rx_steer_req_v2 {
>  	u8 hashkey[MANA_HASH_KEY_SIZE];
>  	u8 cqe_coalescing_enable;
>  	u8 reserved2[7];
> +	mana_handle_t indir_tab[] __counted_by(num_indir_entries);
>  }; /* HW DATA */
>  
>  struct mana_cfg_rx_steer_resp {
> -- 
> 2.25.1
> 

Thanks
Justin