diff mbox series

[net-next] net: ethernet: renesas: Fix return type of rswitch_start_xmit()

Message ID 20221103220032.2142122-1-nathan@kernel.org
State New
Headers
Series [net-next] net: ethernet: renesas: Fix return type of rswitch_start_xmit() |

Commit Message

Nathan Chancellor Nov. 3, 2022, 10 p.m. UTC 
  With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed. A
proposed warning in clang aims to catch these at compile time, which
reveals:

  drivers/net/ethernet/renesas/rswitch.c:1533:20: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
          .ndo_start_xmit = rswitch_start_xmit,
                          ^~~~~~~~~~~~~~~~~~
  1 error generated.

->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
'netdev_tx_t', not 'int'. Adjust the return type of rswitch_start_xmit()
to match the prototype's to resolve the warning and CFI failure.

Link: https://github.com/ClangBuiltLinux/linux/issues/1750
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/net/ethernet/renesas/rswitch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: ef2dd61af7366e5a42e828fff04932e32eb0eacc

Comments

Yoshihiro Shimoda Nov. 4, 2022, 4:29 a.m. UTC | #1 
Hi, Nathan,

> From: Nathan Chancellor, Sent: Friday, November 4, 2022 7:01 AM
> 
> With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> indirect call targets are validated against the expected function
> pointer prototype to make sure the call target is valid to help mitigate
> ROP attacks. If they are not identical, there is a failure at run time,
> which manifests as either a kernel panic or thread getting killed. A
> proposed warning in clang aims to catch these at compile time, which
> reveals:
> 
>   drivers/net/ethernet/renesas/rswitch.c:1533:20: error: incompatible function pointer types initializing 'netdev_tx_t
> (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an
> expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
>           .ndo_start_xmit = rswitch_start_xmit,
>                           ^~~~~~~~~~~~~~~~~~
>   1 error generated.
> 
> ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
> 'netdev_tx_t', not 'int'. Adjust the return type of rswitch_start_xmit()
> to match the prototype's to resolve the warning and CFI failure.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1750
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---

Thank you for the patch!

Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Best regards,
Yoshihiro Shimoda

>  drivers/net/ethernet/renesas/rswitch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index 20df2020d3e5..f0168fedfef9 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -1390,7 +1390,7 @@ static int rswitch_stop(struct net_device *ndev)
>  	return 0;
>  };
> 
> -static int rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev)
> +static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>  {
>  	struct rswitch_device *rdev = netdev_priv(ndev);
>  	struct rswitch_gwca_queue *gq = rdev->tx_queue;
> 
> base-commit: ef2dd61af7366e5a42e828fff04932e32eb0eacc
> --
> 2.38.1
Kees Cook Nov. 4, 2022, 7:16 p.m. UTC | #2 
On Thu, Nov 03, 2022 at 03:00:32PM -0700, Nathan Chancellor wrote:
> With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> indirect call targets are validated against the expected function
> pointer prototype to make sure the call target is valid to help mitigate
> ROP attacks. If they are not identical, there is a failure at run time,
> which manifests as either a kernel panic or thread getting killed. A
> proposed warning in clang aims to catch these at compile time, which
> reveals:
> 
>   drivers/net/ethernet/renesas/rswitch.c:1533:20: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
>           .ndo_start_xmit = rswitch_start_xmit,
>                           ^~~~~~~~~~~~~~~~~~
>   1 error generated.
> 
> ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
> 'netdev_tx_t', not 'int'. Adjust the return type of rswitch_start_xmit()
> to match the prototype's to resolve the warning and CFI failure.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1750
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>
patchwork-bot+netdevbpf@kernel.org Nov. 5, 2022, 2:40 a.m. UTC | #3 
Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu,  3 Nov 2022 15:00:32 -0700 you wrote:
> With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> indirect call targets are validated against the expected function
> pointer prototype to make sure the call target is valid to help mitigate
> ROP attacks. If they are not identical, there is a failure at run time,
> which manifests as either a kernel panic or thread getting killed. A
> proposed warning in clang aims to catch these at compile time, which
> reveals:
> 
> [...]

Here is the summary with links:
  - [net-next] net: ethernet: renesas: Fix return type of rswitch_start_xmit()
    https://git.kernel.org/netdev/net-next/c/8e0aa1ff44ca

You are awesome, thank you!
diff mbox series

Patch

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index 20df2020d3e5..f0168fedfef9 100644
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1390,7 +1390,7 @@  static int rswitch_stop(struct net_device *ndev)
 	return 0;
 };
 
-static int rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 {
 	struct rswitch_device *rdev = netdev_priv(ndev);
 	struct rswitch_gwca_queue *gq = rdev->tx_queue;