From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D74DD1F4188; Tue, 15 Apr 2025 16:19:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744733966; cv=none; b=U4LfdMSCc1lQNAN4vcayZ9IZRjxvB1LAc8Hc/IgQvXQN8RUodEdiyUOGK2U5LnaO9QouoS79YBFcK9dycumkuhu0XJUxt+gPeSTH41ZxiG+PAzRlH3qeNDTceO54aZXW88LFqnUu6g+XOrjbHDTC62PdzZfme1B3CxtCaecqoKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744733966; c=relaxed/simple; bh=ZZU+HEFLzUVha5RjZfYMMSbZbRdTihiRbwfO8ZnjQRc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=a8Rtj5j1BFj8JtsbxaZLApPrND+4jRAnmQEtgl4P/vpqanRm9eb20j+6lWmwMRKfs4Wpg5kBWEktN64UBY43COy5UExdEatxvv3KxhvX8DHVsMXtG9/pRBDjiMj/ZoVnU4zqcgDEM+IUaI1V6Y/d/1teIcGHLMFx2ADSBS5F4tY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J37axF8I; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J37axF8I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B589FC4CEEB; Tue, 15 Apr 2025 16:19:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744733965; bh=ZZU+HEFLzUVha5RjZfYMMSbZbRdTihiRbwfO8ZnjQRc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=J37axF8IBClP0d4y3lbEAVnpkI6azRXPAkNhp150ui/OB9JZKA3ohLd/rrCRV3IXs 0PfbDyVx8yV4IijBEfZMInp4i+w4X0e+N0h+FyR0DPwI1IJftyEQ7sOMFIvh2OKkTW ly9nNNfYKyqtG+8lNYtlBPVpRE7cWE6LLXXI0qLb6AFwtoX7fD0tzBnCOjYf4FEaG+ 2EBMYGhTRnT9vo++GDixpmBkS76/CVKlTJLMYRUw5qyVD1lnqT7cUPRBxjMYKfMRrA xZ9Bctw9/VJmLDHSdB+HA+iY5qwuRzjxqgFA+kgLTj/A7NkFPXaW+u0VRuCcj6YgQc OABCwj77wO8gQ== Date: Tue, 15 Apr 2025 09:19:20 -0700 From: Nathan Chancellor To: Kees Cook Cc: stable@vger.kernel.org, kernel test robot , Marcel Holtmann , Luiz Augusto von Dentz , Josh Poimboeuf , Peter Zijlstra , linux-bluetooth@vger.kernel.org, Bill Wendling , Justin Stitt , Manish Mandlik , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org Subject: Re: [PATCH] Bluetooth: vhci: Avoid needless snprintf() calls Message-ID: <20250415161920.GA1692211@ax162> References: <20250415161518.work.889-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250415161518.work.889-kees@kernel.org> On Tue, Apr 15, 2025 at 09:15:19AM -0700, Kees Cook wrote: > Avoid double-copying of string literals. Use a "const char *" for each > string instead of copying from .rodata into stack and then into the skb. > We can go directly from .rodata to the skb. > > This also works around a Clang bug (that has since been fixed[1]). > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/ > Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support") > Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1] > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook Reviewed-by: Nathan Chancellor > --- > Cc: Marcel Holtmann > Cc: Luiz Augusto von Dentz > Cc: Josh Poimboeuf > Cc: Nathan Chancellor > Cc: Peter Zijlstra > Cc: linux-bluetooth@vger.kernel.org > --- > drivers/bluetooth/hci_vhci.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c > index 7651321d351c..9ac22e4a070b 100644 > --- a/drivers/bluetooth/hci_vhci.c > +++ b/drivers/bluetooth/hci_vhci.c > @@ -289,18 +289,18 @@ static void vhci_coredump(struct hci_dev *hdev) > > static void vhci_coredump_hdr(struct hci_dev *hdev, struct sk_buff *skb) > { > - char buf[80]; > + const char *buf; > > - snprintf(buf, sizeof(buf), "Controller Name: vhci_ctrl\n"); > + buf = "Controller Name: vhci_ctrl\n"; > skb_put_data(skb, buf, strlen(buf)); > > - snprintf(buf, sizeof(buf), "Firmware Version: vhci_fw\n"); > + buf = "Firmware Version: vhci_fw\n"; > skb_put_data(skb, buf, strlen(buf)); > > - snprintf(buf, sizeof(buf), "Driver: vhci_drv\n"); > + buf = "Driver: vhci_drv\n"; > skb_put_data(skb, buf, strlen(buf)); > > - snprintf(buf, sizeof(buf), "Vendor: vhci\n"); > + buf = "Vendor: vhci\n"; > skb_put_data(skb, buf, strlen(buf)); > } > > -- > 2.34.1 >