From patchwork Wed Jul 5 14:02:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 699924 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B299EB64DA for ; Wed, 5 Jul 2023 14:02:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232125AbjGEOCx (ORCPT ); Wed, 5 Jul 2023 10:02:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231865AbjGEOCv (ORCPT ); Wed, 5 Jul 2023 10:02:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FB6211B; Wed, 5 Jul 2023 07:02:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AC71A61568; Wed, 5 Jul 2023 14:02:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE4E5C433C7; Wed, 5 Jul 2023 14:02:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688565769; bh=8Pv519rVX2nyzfcP+WWJAfxHrjLTPQrVejjsds7b0e8=; h=From:To:Cc:Subject:Date:From; b=bTRx9QYeOOUu652xyFmZdnhpFBlT1LXlf0Ecjj9AqPmaZ+k4P5cbVpk6enhALEj+4 a++Be9rRcL1yiFdllRaQpJkGq+/dACPEV0zCo8uGcqIMkwlkcT4Ast+4B3zEqtA1my 1yBNwB/rHhuV7+nPSGNDHyjhl1Y31bpbXvZr1mlYn5elxSVYB5RM2nn4wn9qN5bmxL FhXk8K0TM+LeSS3LrDieZiEoszeAJyznP28Jfz7n7JlnTk3REgjOePQES9Lrc3TQHq SlhmZXawVNCyXfrzkOfyjPxviE83s/157jrxJcl8wZPOP79iNgmJs7hVoxKps5UvLW XTlf78IsOIZ2w== From: Arnd Bergmann To: Jiri Kosina , Benjamin Tissoires Cc: Arnd Bergmann , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Paulo Miguel Almeida , Michael Kelley , Dawei Li , Yang Yingliang , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= , linux-hyperv@vger.kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] HID: hyperv: avoid struct memcpy overrun warning Date: Wed, 5 Jul 2023 16:02:24 +0200 Message-Id: <20230705140242.844167-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org From: Arnd Bergmann A previous patch addressed the fortified memcpy warning for most builds, but I still see this one with gcc-9: In file included from include/linux/string.h:254, from drivers/hid/hid-hyperv.c:8: In function 'fortify_memcpy_chk', inlined from 'mousevsc_on_receive' at drivers/hid/hid-hyperv.c:272:3: include/linux/fortify-string.h:583:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 583 | __write_overflow_field(p_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ My guess is that the WARN_ON() itself is what confuses gcc, so it no longer sees that there is a correct range check. Rework the code in a way that helps readability and avoids the warning. Fixes: 542f25a944715 ("HID: hyperv: Replace one-element array with flexible-array member") Signed-off-by: Arnd Bergmann Reviewed-by: Michael Kelley --- drivers/hid/hid-hyperv.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c index 49d4a26895e76..f33485d83d24f 100644 --- a/drivers/hid/hid-hyperv.c +++ b/drivers/hid/hid-hyperv.c @@ -258,19 +258,17 @@ static void mousevsc_on_receive(struct hv_device *device, switch (hid_msg_hdr->type) { case SYNTH_HID_PROTOCOL_RESPONSE: + len = struct_size(pipe_msg, data, pipe_msg->size); + /* * While it will be impossible for us to protect against * malicious/buggy hypervisor/host, add a check here to * ensure we don't corrupt memory. */ - if (struct_size(pipe_msg, data, pipe_msg->size) - > sizeof(struct mousevsc_prt_msg)) { - WARN_ON(1); + if (WARN_ON(len > sizeof(struct mousevsc_prt_msg))) break; - } - memcpy(&input_dev->protocol_resp, pipe_msg, - struct_size(pipe_msg, data, pipe_msg->size)); + memcpy(&input_dev->protocol_resp, pipe_msg, len); complete(&input_dev->wait_event); break;