From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2526A606A31C for ; Thu, 29 Oct 2026 20:38:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oVdw61b8 Received: by kanga.kvack.org (Postfix) id 443B06B05B4; Thu, 29 Oct 2026 16:38:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 41B4F6B05D2; Thu, 29 Oct 2026 16:38:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3319E6B05D3; Thu, 29 Oct 2026 16:38:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 13B5D6B05B4 for ; Thu, 29 Oct 2026 16:38:43 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id AD081A80EB for ; Thu, 29 Oct 2026 20:38:42 +0000 (UTC) X-FDA: 85376827284.04.B063B1F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf20.hostedemail.com (Postfix) with ESMTP id E15111C0004 for ; Thu, 29 Oct 2026 20:38:40 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=oVdw61b8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf20.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793306321; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=hUEcnN9ydaxDMlr7FSPNgc2BgiAcB7rSVu3xqMV261g=; b=Vcrkqy1DQAoDDMC5KFgwFzNGLYGd//9QZIhd5WSxwb1xHLGDKqzlmWPaA/iFKnpzSIi5Sb UgRFDOM20RNcm5y63a4MrEnY2ik3fIOwgHLGP97XgKO4XV7YCQBgROceMNEFBQgNruEoSP 7YKPyW+do3nasMcc0lF3+iboaBwXJKU= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=oVdw61b8; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf20.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793306321; b=TwRl50/SKXG4TQrQXwDWaOTk+931YOgk6bXtrTnqYVoz63LqwgXSJXW5AvMALNvPFrjv2A U6E7aIr3Q00ELZn7NtmRt2ld8XYdJUZJtEfiopL9Hh5L+eXpc0Vs6LPDWIMewp1vT0QL+1 KwST49ExNZ+tT2ax/SY60GpEu6wzvxU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1EBB140730; Thu, 29 Oct 2026 20:38:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCF331F01825; Thu, 29 Oct 2026 20:38:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306320; bh=hUEcnN9ydaxDMlr7FSPNgc2BgiAcB7rSVu3xqMV261g=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=oVdw61b8fprlozgBHncc41LpdVLG5SLHt1W2WOHHdwpmEHY1UxuvvBPOvqfUxJ6TE ypj1G/DGtqCz4M/Mncb0zLIyJD7YZU5Q9CwKBWyL9J9dnBrvu/xczhapnmY6bqMauH cFW+yKoFtTCsaGgX0DaGpv7jF2hxRsfJnJ0YRpK3Cjo5KggitCplBM2+XWYS/AUOMh 5Qtft9UTttmKosFmaVLBtNXQus22sqElhihxeqFdjS/65EW05g7NDzHOAN3aITVvcf pDVlw7VhPB6Fkbvk3twLQO4Jx+uPVK41BSLLOJJbyUqRT/3NwuiE1YXtG+OOAUcs+j AEGV44bySO/jQ== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:16 +0100 Subject: [PATCH v2 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: <20261029-fixes_core-v2-21-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1263; i=david@kernel.org; h=from:subject:message-id; bh=nCaomD0R1GmRaMbC4ikA/oDPAe1RZtNKP6V5LWq8bsk=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer227ZSqbsjfo/PkOsbOhrnde/K8U2hdmLqwoELi84 uqRtBdJHaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzk8WlGhuutW1yb5HykeVbc c+eWPREaIBpb4SyWKbC8rZtNv2v1F0aGKVM/LJjuEBViqMyy/c3RD1erLQu2rvZ/6eWeIbAgyci XEwA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E15111C0004 X-Stat-Signature: fkuwq1pwy1h6t3dcgnwdrmpcxzj4csgy X-Spam-Status: No, score=-18.8 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_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793306320-293677 X-HE-Meta: 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 aRtZYJdH UUSoDwMOVQIt9bWUDqVvH1kTK9UTAMu5+EZH/YLCyD9rG4/bQrerqK3Xbr/CLzQV8TTbI/f1hEe7tSW3EU1fWLUELtM4W22Kh7wZbGACk+fbPWHj9b0R9NcNJUvCYT7CvvffIT8ZPqWbSm8n6hWsOKnedBQLe+rJ6MI5GZSlKQ80whA/GZ4Rk7Wy82Zap1dY+Heh6ju/COMfSltW9I5HqLmlQDcvQt1AA2yeQTEhUtzAnf2EEQjFwveGbj2kdGYtZ6UkTd80+7e+RZKb7bXS45CqbJxTTxcxD5eauIKSnj2GnUKV5GV5cs0UNwTZ5fq0b3U58lSr1jbQJ3SIrQmqRWCLSkakV6z+c0IbnzwR5B1h156I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: 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 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 cc4fa18783ce..1c2ac7c66c30 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