From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 078EBC4167B for ; Tue, 5 Dec 2023 17:53:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7NBXt9xmAEkSUxu7YsZNQfOqx5RZWDv7vzb28/ySBQE=; b=KJvW9NjwhHyTMz/Djp9MsV5x8A ZAMHT2+zSXTOoeHFyoq3CxZS2rJ1ulniLWYhS/JhjPoj1D3PddreJ0/hsuyqZ7yQStCPG0Q31HHE/ rvVmb45Hsce/dEr4vD9SeBsF6mwGpT+mgle5tt2gNT0VSvpIU9ZXSeg3YrIUUt5jBGgVga60c3sox BSIY4KusvhgEl34HPKpMCUT7gAHAhwt/s8M4+xGNVoFJvFdSbguHawfVmc3EdKb1O7CB/YTMdtzdC a3iQBza++Oa6DRzTBxQpLO10bQnFhP2yeB2n7Sb6ozVEdTcw7BaKEvfv+EkjGWF9LBdxjIc98CNge fNaAeDIQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rAZbb-00855I-2L; Tue, 05 Dec 2023 17:53:11 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rAZbX-00854m-30 for linux-um@lists.infradead.org; Tue, 05 Dec 2023 17:53:09 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id DE963CE19F4; Tue, 5 Dec 2023 17:53:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99653C433C8; Tue, 5 Dec 2023 17:53:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701798785; bh=qND1Cy64uVoi7dcRD4f9PhuWzWNexF0SFLJhlxPZ91E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bOHvhhhGxvy2Z/wb90CKjL692W3BqYaNIrPBlQ8ImdyJIOGtjD2j7xMkgGxaMhwXY kuQgjFkYAtPqKyCh+i4sbbU9AG9ZdJez5q9PL41RjRm1ErlRBqIYPEu6k0e02lLhM+ aunfDl2k5E/MtUGpqtUdJ1blRg4NVZX8tdW5gqyY2FLk6MBHa/bQHiqK4ioRuGExQL /Ce9YdeDBNPfVf6BNBOuVMw5uaTnSM2pZMmwaXZi59+56lmcGv28gkYmhoYoBqZsRB 3R7j/RRT3DyigF/LuAdEK4Nj7d+x5uL4nQSQ8uj1XzadQYLqbBZIhIYzLZSN5kWL0q T1OMbB5r4kInw== Date: Tue, 5 Dec 2023 10:53:02 -0700 From: Nathan Chancellor To: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net Cc: ndesaulniers@google.com, trix@redhat.com, linux-um@lists.infradead.org, llvm@lists.linux.dev, patches@lists.linux.dev, kernel test robot Subject: Re: [PATCH] um: net: Fix return type of uml_net_start_xmit() Message-ID: <20231205175302.GA536347@dev-arch.thelio-3990X> References: <20231003-um-net-wifpts-v1-1-02888c634ee7@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231003-um-net-wifpts-v1-1-02888c634ee7@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231205_095308_426389_FD949A23 X-CRM114-Status: GOOD ( 23.40 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org Ping? I would like to turn this warning on for W=1 and the kbuild test robot flagged this instance. If the UML folks don't want to carry it, could I get an ack so that it could go with the warning enablement in the kbuild tree? https://lore.kernel.org/20231002-enable-wincompatible-function-pointer-types-strict-w-1-v1-1-808ab955d42d@kernel.org/ On Tue, Oct 03, 2023 at 11:35:53AM -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 > warning in clang aims to catch these at compile time, which reveals: > > arch/um/drivers/net_kern.c:353:21: warning: 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 *)' [-Wincompatible-function-pointer-types-strict] > 353 | .ndo_start_xmit = uml_net_start_xmit, > | ^~~~~~~~~~~~~~~~~~ > 1 warning generated. > > ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of > 'netdev_tx_t', not 'int'. Adjust the return type of uml_net_start_xmit() > to match the prototype's to resolve the warning. While UML does not > currently implement support for kCFI, it could in the future, which > means this warning becomes a fatal CFI failure at run time. > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202310031340.v1vPh207-lkp@intel.com/ > Signed-off-by: Nathan Chancellor > --- > arch/um/drivers/net_kern.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c > index 3d7836c46507..cabcc501b448 100644 > --- a/arch/um/drivers/net_kern.c > +++ b/arch/um/drivers/net_kern.c > @@ -204,7 +204,7 @@ static int uml_net_close(struct net_device *dev) > return 0; > } > > -static int uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) > +static netdev_tx_t uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) > { > struct uml_net_private *lp = netdev_priv(dev); > unsigned long flags; > > --- > base-commit: 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa > change-id: 20231003-um-net-wifpts-14a7429c7524 > > Best regards, > -- > Nathan Chancellor >