Patch "hamradio: baycom_epp: Fix return type of baycom_send_packet()" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    hamradio: baycom_epp: Fix return type of baycom_send_packet()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hamradio-baycom_epp-fix-return-type-of-baycom_send_p.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 763684053035814b37ca14904ba68d597de1e42e
Author: Nathan Chancellor <nathan@xxxxxxxxxx>
Date:   Wed Nov 2 09:06:10 2022 -0700

    hamradio: baycom_epp: Fix return type of baycom_send_packet()
    
    [ Upstream commit c5733e5b15d91ab679646ec3149e192996a27d5d ]
    
    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/hamradio/baycom_epp.c:1119:25: 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      = baycom_send_packet,
                                    ^~~~~~~~~~~~~~~~~~
      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 baycom_send_packet()
    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>
    Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221102160610.1186145-1-nathan@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 1e62d00732f2..787eaf3f4f13 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -772,7 +772,7 @@ static void epp_bh(struct work_struct *work)
  * ===================== network driver interface =========================
  */
 
-static int baycom_send_packet(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t baycom_send_packet(struct sk_buff *skb, struct net_device *dev)
 {
 	struct baycom_state *bc = netdev_priv(dev);