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* [PATCH][next] net: spider_net: Use size_add() in call to struct_size()
@ 2023-09-15 19:25 Gustavo A. R. Silva
  2023-09-15 19:53 ` Kees Cook
  2023-09-16  0:21 ` Geoff Levand
  0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2023-09-15 19:25 UTC (permalink / raw)
  To: Ishizaki Kou, Geoff Levand, David S. Miller, Eric Dumazet,
	Jakub Kicinski, Paolo Abeni, Gustavo A. R. Silva
  Cc: linux-hardening, netdev, linuxppc-dev, linux-kernel,
	Gustavo A. R. Silva

If, for any reason, the open-coded arithmetic causes a wraparound,
the protection that `struct_size()` adds against potential integer
overflows is defeated. Fix this by hardening call to `struct_size()`
with `size_add()`.

Fixes: 3f1071ec39f7 ("net: spider_net: Use struct_size() helper")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/net/ethernet/toshiba/spider_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/toshiba/spider_net.c b/drivers/net/ethernet/toshiba/spider_net.c
index 50d7eacfec58..87e67121477c 100644
--- a/drivers/net/ethernet/toshiba/spider_net.c
+++ b/drivers/net/ethernet/toshiba/spider_net.c
@@ -2332,7 +2332,7 @@ spider_net_alloc_card(void)
 	struct spider_net_card *card;
 
 	netdev = alloc_etherdev(struct_size(card, darray,
-					    tx_descriptors + rx_descriptors));
+					    size_add(tx_descriptors, rx_descriptors)));
 	if (!netdev)
 		return NULL;
 
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH][next] net: spider_net: Use size_add() in call to struct_size()
  2023-09-15 19:25 [PATCH][next] net: spider_net: Use size_add() in call to struct_size() Gustavo A. R. Silva
@ 2023-09-15 19:53 ` Kees Cook
  2023-09-16  0:21 ` Geoff Levand
  1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2023-09-15 19:53 UTC (permalink / raw)
  To: Gustavo A. R. Silva
  Cc: Gustavo A. R. Silva, Geoff Levand, netdev, linux-kernel,
	Eric Dumazet, linux-hardening, Jakub Kicinski, Paolo Abeni,
	linuxppc-dev, David S. Miller

On Fri, Sep 15, 2023 at 01:25:36PM -0600, Gustavo A. R. Silva wrote:
> If, for any reason, the open-coded arithmetic causes a wraparound,
> the protection that `struct_size()` adds against potential integer
> overflows is defeated. Fix this by hardening call to `struct_size()`
> with `size_add()`.
> 
> Fixes: 3f1071ec39f7 ("net: spider_net: Use struct_size() helper")
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH][next] net: spider_net: Use size_add() in call to struct_size()
  2023-09-15 19:25 [PATCH][next] net: spider_net: Use size_add() in call to struct_size() Gustavo A. R. Silva
  2023-09-15 19:53 ` Kees Cook
@ 2023-09-16  0:21 ` Geoff Levand
  1 sibling, 0 replies; 3+ messages in thread
From: Geoff Levand @ 2023-09-16  0:21 UTC (permalink / raw)
  To: Gustavo A. R. Silva, Ishizaki Kou, David S. Miller, Eric Dumazet,
	Jakub Kicinski, Paolo Abeni, Gustavo A. R. Silva
  Cc: netdev, linuxppc-dev, linux-kernel, linux-hardening

On 9/15/23 14:25, Gustavo A. R. Silva wrote:
> If, for any reason, the open-coded arithmetic causes a wraparound,
> the protection that `struct_size()` adds against potential integer
> overflows is defeated. Fix this by hardening call to `struct_size()`
> with `size_add()`.
> 
> Fixes: 3f1071ec39f7 ("net: spider_net: Use struct_size() helper")
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
>  drivers/net/ethernet/toshiba/spider_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/toshiba/spider_net.c b/drivers/net/ethernet/toshiba/spider_net.c
> index 50d7eacfec58..87e67121477c 100644
> --- a/drivers/net/ethernet/toshiba/spider_net.c
> +++ b/drivers/net/ethernet/toshiba/spider_net.c
> @@ -2332,7 +2332,7 @@ spider_net_alloc_card(void)
>  	struct spider_net_card *card;
>  
>  	netdev = alloc_etherdev(struct_size(card, darray,
> -					    tx_descriptors + rx_descriptors));
> +					    size_add(tx_descriptors, rx_descriptors)));
>  	if (!netdev)
>  		return NULL;
>  

Looks good to me.  Thanks for your fix-up.

Signed-off-by: Geoff Levand <geoff@infradead.org>



^ permalink raw reply	[flat|nested] 3+ messages in thread

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2023-09-15 19:53 ` Kees Cook
2023-09-16  0:21 ` Geoff Levand

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