The ndo_start_xmit field in net_device_ops is expected to be of type
netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).

The mismatched return type breaks forward edge kCFI since the underlying
function definition does not match the function hook definition.

The return type of dm9000_start_xmit should be changed from int to
netdev_tx_t.

Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1703
Cc: llvm@lists.linux.dev
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
---
 drivers/net/ethernet/davicom/dm9000.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/davicom/dm9000.c b/drivers/net/ethernet/davicom/dm9000.c
index 0985ab216566..186a5e0a7862 100644
--- a/drivers/net/ethernet/davicom/dm9000.c
+++ b/drivers/net/ethernet/davicom/dm9000.c
@@ -1012,7 +1012,7 @@ static void dm9000_send_packet(struct net_device *dev,
  *  Hardware start transmission.
  *  Send a packet to media from the upper layer.
  */
-static int
+static netdev_tx_t
 dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	unsigned long flags;
-- 
2.37.2.789.g6183377224-goog

Hello:

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

On Mon, 12 Sep 2022 12:47:19 -0700 you wrote:
> The ndo_start_xmit field in net_device_ops is expected to be of type
> netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).
> 
> The mismatched return type breaks forward edge kCFI since the underlying
> function definition does not match the function hook definition.
> 
> The return type of dm9000_start_xmit should be changed from int to
> netdev_tx_t.
> 
> [...]

Here is the summary with links:
  - net: davicom: Fix return type of dm9000_start_xmit
    https://git.kernel.org/netdev/net-next/c/0191580b000d

You are awesome, thank you!
-- 
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On Mon, Sep 12, 2022 at 12:47:19PM -0700, Nathan Huckleberry wrote:
> The ndo_start_xmit field in net_device_ops is expected to be of type
> netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).
> 
> The mismatched return type breaks forward edge kCFI since the underlying
> function definition does not match the function hook definition.
> 
> The return type of dm9000_start_xmit should be changed from int to
> netdev_tx_t.
> 
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1703
> Cc: llvm@lists.linux.dev
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/net/ethernet/davicom/dm9000.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/davicom/dm9000.c b/drivers/net/ethernet/davicom/dm9000.c
> index 0985ab216566..186a5e0a7862 100644
> --- a/drivers/net/ethernet/davicom/dm9000.c
> +++ b/drivers/net/ethernet/davicom/dm9000.c
> @@ -1012,7 +1012,7 @@ static void dm9000_send_packet(struct net_device *dev,
>   *  Hardware start transmission.
>   *  Send a packet to media from the upper layer.
>   */
> -static int
> +static netdev_tx_t
>  dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  {
>  	unsigned long flags;
> -- 
> 2.37.2.789.g6183377224-goog
>