From nobody Fri Dec 19 03:08:52 2025 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 1DD84C5AD4C for ; Sun, 19 Nov 2023 19:48:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229959AbjKSTsL (ORCPT ); Sun, 19 Nov 2023 14:48:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229665AbjKSTsJ (ORCPT ); Sun, 19 Nov 2023 14:48:09 -0500 Received: from mail-il1-x133.google.com (mail-il1-x133.google.com [IPv6:2607:f8b0:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E008211A for ; Sun, 19 Nov 2023 11:48:05 -0800 (PST) Received: by mail-il1-x133.google.com with SMTP id e9e14a558f8ab-357cc880bd8so14138705ab.0 for ; Sun, 19 Nov 2023 11:48:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700423285; x=1701028085; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to; bh=tM0GQjuVnFv7RufWXzCKq9li8NCfwru2okUxp/uvL+E=; b=bQbQ3YTvLIP9LH2t1GMs9zqgejkdaGNPxoDVKKh73N5sqhbbjr8T6V8/JKDnQabOOh /qRdKJtbeBuVKz6qiLkgB1i/i+neW8S75xSXJ3l6Unn82Qj/mkeUawLjWCa6Jae8iE6Q d47bG2IU4g7wCrGZayiNRT+8QdmukBz5hAlQbze6YsyWinY/5XOIImih14QN9GLMcA6N yJpz0WDO4TpISDbkVkKip/X64Q2twM4B/o1Yz7Ep5t13eEoLwJoljNgQBOVvvFBUi2t0 oIzwf5HvzXOT4ZWxSHh+ggG3pSD624M+HRrNDoPEmrogKKVAPm3xTaQ4w6xNohGPbxvV n2LQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700423285; x=1701028085; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=tM0GQjuVnFv7RufWXzCKq9li8NCfwru2okUxp/uvL+E=; b=DfHFiiH72e5TOK7Zq8n4zpmve9Q34oPdBKUOZuBIfId2Y2a+HWlXlgDSrWq6ZYnnIV mj9vsl2cYP2B0Miz6hN1eMewBmNXG63IPjuFpbz4UmeE3KmPO5rMiEStgioDox55xdq2 8faPFb7xR14lUllobk+WJGTI3wxmfa3SS/N5E3OzEcJKD62cyItlVh98v3gdvnY2UR00 qxcY1C0W4p3Td4+fdUMTULPBHCcy0uHvcDxsc62+2PskX18UZZFDbBqYtyPvlbYx/zUT rWo0uqzsT8tCfZV5LpcqYUKHK0mpJSmpUHMbTkDrURVCScq2qPxBctMVjPKws/5CfFAx uqfg== X-Gm-Message-State: AOJu0YxsnnAxhFbBWO2h8Rd2pgVIY1p03Tgv+pKpX5nFF7PpL6YR1yM2 RwsPqK7R9cTzGT5EHvaBh7I= X-Google-Smtp-Source: AGHT+IF1UkKRv/ipdxof7nKQAoicjYZ8F2kSET5NL02/aAVKfiSk21ZO3YlPkVn68ZksUna/3gG5lw== X-Received: by 2002:a92:c26d:0:b0:35b:695:c3c8 with SMTP id h13-20020a92c26d000000b0035b0695c3c8mr353889ild.9.1700423285183; Sun, 19 Nov 2023 11:48:05 -0800 (PST) Received: from KASONG-MB2.tencent.com ([115.171.40.79]) by smtp.gmail.com with ESMTPSA id a6-20020aa78646000000b006cb7feae74fsm1237140pfo.164.2023.11.19.11.48.02 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 19 Nov 2023 11:48:04 -0800 (PST) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , "Huang, Ying" , David Hildenbrand , Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH 01/24] mm/swap: fix a potential undefined behavior issue Date: Mon, 20 Nov 2023 03:47:17 +0800 Message-ID: <20231119194740.94101-2-ryncsn@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231119194740.94101-1-ryncsn@gmail.com> References: <20231119194740.94101-1-ryncsn@gmail.com> Reply-To: Kairui Song MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Kairui Song When folio is NULL, taking the address of its struct member is an undefined behavior, the UB is caused by applying -> operator to a pointer not pointing to any object. Although in practice this won't lead to a real issue, still better to fix it, also makes the code less error-prone, when folio is NULL, page is also NULL, instead of a meanless offset value. Signed-off-by: Kairui Song --- mm/memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index e27e2e5beb3f..70ffa867b1be 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3861,7 +3861,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) /* skip swapcache */ folio =3D vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vmf->address, false); - page =3D &folio->page; if (folio) { __folio_set_locked(folio); __folio_set_swapbacked(folio); @@ -3879,6 +3878,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) workingset_refault(folio, shadow); =20 folio_add_lru(folio); + page =3D &folio->page; =20 /* To provide entry to swap_readpage() */ folio->swap =3D entry; --=20 2.42.0