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@xxxxxxxxxx> > --- Thank you for the patch! Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> 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
