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* [PATCH] net: ethernet: ti: Fix return type of netcp_ndo_start_xmit()
@ 2022-11-02 16:09 Nathan Chancellor
  2022-11-02 19:08 ` Kees Cook
  2022-11-04  5:00 ` patchwork-bot+netdevbpf
  0 siblings, 2 replies; 3+ messages in thread
From: Nathan Chancellor @ 2022-11-02 16:09 UTC (permalink / raw)
  To: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni
  Cc: netdev, Nick Desaulniers, Tom Rix, Kees Cook, Sami Tolvanen,
	llvm, linux-kernel, patches, Nathan Chancellor

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

  drivers/net/ethernet/ti/netcp_core.c:1944:21: 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         = netcp_ndo_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
netcp_ndo_start_xmit() to match the prototype's to resolve the warning
and CFI failure.

Signed-off-by: Nathan Chancellor <>
 drivers/net/ethernet/ti/netcp_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index aba70bef4894..9eb9eaff4dc9 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -1261,7 +1261,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 /* Submit the packet */
-static int netcp_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t netcp_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	struct netcp_intf *netcp = netdev_priv(ndev);
 	struct netcp_stats *tx_stats = &netcp->stats;

base-commit: 9abf2313adc1ca1b6180c508c25f22f9395cc780

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

end of thread, other threads:[~2022-11-04  5:00 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-11-02 16:09 [PATCH] net: ethernet: ti: Fix return type of netcp_ndo_start_xmit() Nathan Chancellor
2022-11-02 19:08 ` Kees Cook
2022-11-04  5:00 ` patchwork-bot+netdevbpf

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