From patchwork Mon Jul 12 06:04:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 473995 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD863C11F69 for ; Mon, 12 Jul 2021 07:10:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A528861370 for ; Mon, 12 Jul 2021 07:10:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241698AbhGLHNN (ORCPT ); Mon, 12 Jul 2021 03:13:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:41186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238858AbhGLHIv (ORCPT ); Mon, 12 Jul 2021 03:08:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9B285611C0; Mon, 12 Jul 2021 07:05:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626073501; bh=GsM7kTT8tLZRHnd8pH8qOql2SjIfQ9+HXrYJLfJFeGU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gojLOUWsGg7rtWk5XaRSEfz2kPNJFZlWtkqXAH7uhW3DlOM+nSzBmfgwMycSevRYr oqdnHp+6Cu/sKQwid9GznbLSMehJw40wX2qh6razyQcNMTrKDvenhCAXZDAXs/CMRz WJVSp50vJ5xr+X32w5Gp+tzYiWI257DXco8czwG4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, kernel test robot , Richard Fitzgerald , Petr Mladek , Sasha Levin Subject: [PATCH 5.12 211/700] random32: Fix implicit truncation warning in prandom_seed_state() Date: Mon, 12 Jul 2021 08:04:54 +0200 Message-Id: <20210712060956.682156506@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Richard Fitzgerald [ Upstream commit d327ea15a305024ef0085252fa3657bbb1ce25f5 ] sparse generates the following warning: include/linux/prandom.h:114:45: sparse: sparse: cast truncates bits from constant value This is because the 64-bit seed value is manipulated and then placed in a u32, causing an implicit cast and truncation. A forced cast to u32 doesn't prevent this warning, which is reasonable because a typecast doesn't prove that truncation was expected. Logical-AND the value with 0xffffffff to make explicit that truncation to 32-bit is intended. Reported-by: kernel test robot Signed-off-by: Richard Fitzgerald Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210525122012.6336-3-rf@opensource.cirrus.com Signed-off-by: Sasha Levin --- include/linux/prandom.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/prandom.h b/include/linux/prandom.h index bbf4b4ad61df..056d31317e49 100644 --- a/include/linux/prandom.h +++ b/include/linux/prandom.h @@ -111,7 +111,7 @@ static inline u32 __seed(u32 x, u32 m) */ static inline void prandom_seed_state(struct rnd_state *state, u64 seed) { - u32 i = (seed >> 32) ^ (seed << 10) ^ seed; + u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; state->s1 = __seed(i, 2U); state->s2 = __seed(i, 8U);