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. A new warning in clang will catch this at compile time: drivers/net/ethernet/microsoft/mana/mana_en.c:382:21: 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 = mana_start_xmit, ^~~~~~~~~~~~~~~ 1 error generated. The return type of mana_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 Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Dexuan Cui <decui@microsoft.com> [nathan: Rebase on net-next and resolve conflicts Add note about new clang warning] Signed-off-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20221109002629.1446680-1-nathan@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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