From: Kees Cook <keescook@chromium.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Thomas Sailer <t.sailer@alumni.ethz.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
linux-hams@vger.kernel.org, netdev@vger.kernel.org,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Rix <trix@redhat.com>,
Sami Tolvanen <samitolvanen@google.com>,
llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
patches@lists.linux.dev
Subject: Re: [PATCH] hamradio: baycom_epp: Fix return type of baycom_send_packet()
Date: Wed, 2 Nov 2022 12:08:00 -0700 [thread overview]
Message-ID: <202211021207.E41AE398@keescook> (raw)
In-Reply-To: <20221102160610.1186145-1-nathan@kernel.org>
On Wed, Nov 02, 2022 at 09:06:10AM -0700, Nathan Chancellor wrote:
> 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@kernel.org>
Heh, this one was already using the enum for the argument to "return",
too. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2022-11-02 19:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-02 16:06 [PATCH] hamradio: baycom_epp: Fix return type of baycom_send_packet() Nathan Chancellor
2022-11-02 19:08 ` Kees Cook [this message]
2022-11-04 5:00 ` patchwork-bot+netdevbpf
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