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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C708DC04A68 for ; Wed, 27 Jul 2022 16:43:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240045AbiG0Qnf (ORCPT ); Wed, 27 Jul 2022 12:43:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239761AbiG0QnP (ORCPT ); Wed, 27 Jul 2022 12:43:15 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 096365072E; Wed, 27 Jul 2022 09:30:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A8343B821C8; Wed, 27 Jul 2022 16:30:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5751C433D6; Wed, 27 Jul 2022 16:30:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658939412; bh=4n3VmcxWedC1r5TGuxLLFmXPpspP/C7qwPpncEwq+aU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=goowL7LZcG0X5Upud81b7xmsz4Jh6owBihXOBhEk9XCpBKJWFkpq57BWCBvjYzv8/ fJjA75FF8koyEdhO8LIZI5pALOlp4IvP1FZQx69F+kQPmL9OgRSZ4qd7rIoawiQTdk SysmjncRjiSAwsk3rOkg0683c5mf5FGAl4wYTFCY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Will Deacon , Ard Biesheuvel , Kees Cook , Hanjun Guo , Ard Biesheuvel , Elena Reshetova , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Sasha Levin Subject: [PATCH 5.4 61/87] locking/refcount: Ensure integer operands are treated as signed Date: Wed, 27 Jul 2022 18:10:54 +0200 Message-Id: <20220727161011.522539778@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220727161008.993711844@linuxfoundation.org> References: <20220727161008.993711844@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Will Deacon [ Upstream commit 97a1420adf0cdf0cf6f41bab0b2acf658c96b94b ] In preparation for changing the saturation point of REFCOUNT_FULL to INT_MIN/2, change the type of integer operands passed into the API from 'unsigned int' to 'int' so that we can avoid casting during comparisons when we don't want to fall foul of C integral conversion rules for signed and unsigned types. Since the kernel is compiled with '-fno-strict-overflow', we don't need to worry about the UB introduced by signed overflow here. Furthermore, we're already making heavy use of the atomic_t API, which operates exclusively on signed types. Signed-off-by: Will Deacon Reviewed-by: Ard Biesheuvel Reviewed-by: Kees Cook Tested-by: Hanjun Guo Cc: Ard Biesheuvel Cc: Elena Reshetova Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191121115902.2551-3-will@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- include/linux/refcount.h | 14 +++++++------- lib/refcount.c | 6 +++--- 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 79f62e8d2256..89066a1471dd 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -28,7 +28,7 @@ typedef struct refcount_struct { * @r: the refcount * @n: value to which the refcount will be set */ -static inline void refcount_set(refcount_t *r, unsigned int n) +static inline void refcount_set(refcount_t *r, int n) { atomic_set(&r->refs, n); } @@ -44,13 +44,13 @@ static inline unsigned int refcount_read(const refcount_t *r) return atomic_read(&r->refs); } -extern __must_check bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r); -extern void refcount_add_checked(unsigned int i, refcount_t *r); +extern __must_check bool refcount_add_not_zero_checked(int i, refcount_t *r); +extern void refcount_add_checked(int i, refcount_t *r); extern __must_check bool refcount_inc_not_zero_checked(refcount_t *r); extern void refcount_inc_checked(refcount_t *r); -extern __must_check bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r); +extern __must_check bool refcount_sub_and_test_checked(int i, refcount_t *r); extern __must_check bool refcount_dec_and_test_checked(refcount_t *r); extern void refcount_dec_checked(refcount_t *r); @@ -79,12 +79,12 @@ extern void refcount_dec_checked(refcount_t *r); # ifdef CONFIG_ARCH_HAS_REFCOUNT # include # else -static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r) +static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r) { return atomic_add_unless(&r->refs, i, 0); } -static inline void refcount_add(unsigned int i, refcount_t *r) +static inline void refcount_add(int i, refcount_t *r) { atomic_add(i, &r->refs); } @@ -99,7 +99,7 @@ static inline void refcount_inc(refcount_t *r) atomic_inc(&r->refs); } -static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) +static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r) { return atomic_sub_and_test(i, &r->refs); } diff --git a/lib/refcount.c b/lib/refcount.c index 48b78a423d7d..719b0bc42ab1 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -61,7 +61,7 @@ * * Return: false if the passed refcount is 0, true otherwise */ -bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r) +bool refcount_add_not_zero_checked(int i, refcount_t *r) { unsigned int new, val = atomic_read(&r->refs); @@ -101,7 +101,7 @@ EXPORT_SYMBOL(refcount_add_not_zero_checked); * cases, refcount_inc(), or one of its variants, should instead be used to * increment a reference count. */ -void refcount_add_checked(unsigned int i, refcount_t *r) +void refcount_add_checked(int i, refcount_t *r) { WARN_ONCE(!refcount_add_not_zero_checked(i, r), "refcount_t: addition on 0; use-after-free.\n"); } @@ -180,7 +180,7 @@ EXPORT_SYMBOL(refcount_inc_checked); * * Return: true if the resulting refcount is 0, false otherwise */ -bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r) +bool refcount_sub_and_test_checked(int i, refcount_t *r) { unsigned int new, val = atomic_read(&r->refs); -- 2.35.1