From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96084606A323 for ; Sat, 31 Oct 2026 09:45:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=4z5xvfMD; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=JhV9oGMq DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=foIE8/qjRxOslIMIVm5LWTcoDseO7kpGoD14hc0ILxg=; b=4z5xvfMDoVCXVR q5poxJ7ZrKvE8lA/iwTtGMEr6W6Z5UCv1GjNMI0+0Quk9TWN41UBRHAtQVN0sdgCVdE26GVhQfx6z dFTWNER5P33/k1hpHKTT+jLJclgReYgSJ3Pc5mMW5TNfnkRVBL0B8tdnJT7gCWlwYrAk2g3Bq/TSw OOuTffbUb4M6eOzZjzQqPpchVMfqAvAL2t2dbjeCmjSYNDFtoN8w6edsuc5sCcRIsF9i9UyWOnWPQ ohDse6uk+kkLOieCfCdl3rTlJ+x5QP6bFO8R0StT0vR4XsXHFrDedaAyBBXytnNhx2060dObbc08s W7ovTtXqZTQrm3nuziTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xN5ej-0000000DAI9-1PYw; Sat, 31 Oct 2026 09:45:45 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xN5eh-0000000DAHs-3MZN for kexec@lists.infradead.org; Sat, 31 Oct 2026 09:45:43 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id EFC7C605CF; Sat, 31 Oct 2026 09:45:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D56871F000C1; Sat, 31 Oct 2026 09:45:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439942; bh=foIE8/qjRxOslIMIVm5LWTcoDseO7kpGoD14hc0ILxg=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=JhV9oGMqjIuZGgcbHEUsRikcUmJNTkInVxMbDD2McBF1KHRCOovytr11YurFRKmY+ bzpFUCXJV07KGchANo9OXAYly2i+TAjzzG2qyAyH0zYRfED/AUnwLW/4JR6ep8DOEp 3ob8fsc2zXmkJajPfwx9ACN5aMF4fl4RqsnmBccaStiOm1Ik3W84FuIM9kDgSEnVcs FnUcTU/F9+4T7XCWF7hfPk1mhEKqJzRhHlBbv4kVrzqvgm/NnX6C0xi3dX2J6sa5iR Ryhd7cB6JyGhcESjQmqHd0GH2cyaVRdT7FizFV9PWwZW6Rt8Hkhe6GmVGYIIMTUxku 0gFPxVWBEFA7Q== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:50 +0100 Subject: [PATCH v3 21/47] mm/gup: fix out-of-bounds write for nr_pages == 0 in GUP-fast X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-21-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Chris Mason , stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1320; i=david@kernel.org; h=from:subject:message-id; bh=R62eMdMsJypxqcni0WbltJmOI5kqokR7T4ahYSHS7oQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebk9XufzzUt3qVRK79jW/zlzmvMenZ80MsUTHtrnHE 7tlXOZqdpSyMIhxMMiKKbIEBd83ePlyXW21Gx8zzBxWJpAhDFycAjCRtAqGv6InnopkrO0IDNHq 7pC+cvvWiW0b+d98XM7UJ9iq53RHYQ3Df69HC3Z+ryqu27DmAne4j/fJiz8+bFvAecZ3t5uDiFP eOk4A X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Chris Mason With nr_pages == 0, GUP-fast still enters its page table walk and can write past the caller's page array. The old end <= start check caught empty ranges, but was replaced with an overflow check. Users such as OrangeFS can pass a zero page count derived from a userspace-supplied length. So let's return zero for nr_pages == 0 before starting the walk, just like GUP-slow. Fix generated by an LLM and sent by Chris Mason in private. Fixes: c28b1fc70390 ("mm/gup: reorganize internal_get_user_pages_fast()") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason [ david: simplify description ] Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: Muchun Song Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/gup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index cc4fa18783ce0..1c2ac7c66c309 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3215,6 +3215,9 @@ static int gup_fast_fallback(unsigned long start, unsigned long nr_pages, FOLL_PCI_P2PDMA | FOLL_HONOR_NUMA_FAULT))) return -EINVAL; + if (unlikely(!nr_pages)) + return 0; + if (gup_flags & FOLL_PIN) mm_set_has_pinned_flag(current->mm); -- 2.43.0