From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793439928; b=uuuGLwqWoJtWFr1c3123OIHolHFbBFScXlJ/L6dIENBFxHNOjB40yjxDZkkrHWngXEmM ts5hUixo56zmMKo3thy0tu3xHTLVZuTBYLI85p4kIw9vtYPsNOoO+NRBKBCrG9zsfMGQF /jK1cy3AlqsJ3qWKS8gG690oz27X81E9kQFhz/zWx/OfIR6q1alYyAIRwNwFlrouCwUVq GuZQa3mP3RoWwsSSeNma4BTUunRhAhPlPFtkV3DqibXYmC2boj3azbiU+WW5Ayt4c7y49 rXCYCpytrA2YPDPeYGloR5f/2oBCGP3AEkFmRwIGpL9Iv/CXwg64b5hASPc15rhOmKA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793439928; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=i0fOCg32ZVxaPUOTstAI4PWBunqX+FIUzQ1HDwJNXX0=; b=GGyOUGVSlx6yrVA6VHAepkOE5YgAOyqsB7W6nHxIktWIck2iqlngrAfmz5TpZqS5d9EW F+RdwRrvJAZ3zM5pmnhu5nmLlY6PxQEJD1ihdEkA4PoQ7bXbM2nFYTi51TP+APGJ40Lrl EkEOv2OHxTWaDxZgXNad6Ex05MNFqDfZJn90ilq9muiS7BouNi/WkSXtFWROuusvig0uy euFxHQ0bgFPQJT4Uk6gNt6vx9QlIQ0d8QklHC9+vhQhAE82nUb9W06Kzjtf3GVXg5Dasx Lo+jOTyfk4oZ13NZkSumRuqr2Bk+7y8h+4GtHq4FSFkGPEYm1p4eZRy7BwzXZE58Q8w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="I+u/qiUF"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA55E606A31A; Sat, 31 Oct 2026 09:45:27 +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=I+u/qiUF Received: by smtp.kernel.org (Postfix) with ESMTPSA id DBB241F00A02; Sat, 31 Oct 2026 09:45:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439927; bh=i0fOCg32ZVxaPUOTstAI4PWBunqX+FIUzQ1HDwJNXX0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=I+u/qiUFq55Bqh/mCzeRdaNEZVbWz2Cez27DLAzD/CdZXTyqmB5bYm+Fl6qEmq2Z2 WJvwseUo7zHKYRbWt9Rv4IEnwRIhPvMDh/PKuwrOafaZnW8X/5pqr5Bkq9YF7RmOYS 4Zei8laaNlZyX2P2Q6NUKdD1GbEww9ZjP+y70mr1OQYlD1V64LRxmdqoaSomaV2FtX CQ8Ic3S0l1ZmuJLSZ0I7IOLDDtdlEsNfHC7kEu6Ki9oOfT6r3v2JnYREAy6h6bHLWn X/ei8Nn0JLhG5DT/1yTYHYlsyj1adY19h8G8Oq2LvYsF7hvt7JNDTs8gKO6F2XpwYB apJOtNdWZXBwg== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:49 +0100 Subject: [PATCH v3 20/47] mm/gup: fix clearing folios in memfd_pin_folios() X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-20-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, Samiullah Khawaja , Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1729; i=david@kernel.org; h=from:subject:message-id; bh=xcEwKBas+pY55btjstA9an0JLHBAjCwLiQD85ZwKAMo=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebk/P5eswTLp9ZXLkC/9lrHE/q3ZEFgpdslmWPqPj/ eeCtB8rOkpZGMQ4GGTFFFmCgu8bvHy5rrbajY8ZZg4rE8gQBi5OAZjIgjBGhvvPd/1JS1pZsSZj 4YRAc8n5JzsyOWbXbgkOuvGe5XSddzIjw4NFU/SfrmJzfKdh3SrxLb541d9lcemla96uStcJCCu cww4A X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A From: Chris Mason memfd_pin_folios() pins folios obtained directly from the page cache without checking whether they are uptodate. However, shmem fallocate() can leave newly allocated folios uncleared and not uptodate. Callers such as udmabuf can then expose uninitialized memory to userspace. Clear non-uptodate folios and mark them uptodate under the folio lock before returning them to the caller. Fix generated by an LLM and sent by Chris Mason in private. Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason [ david: simplify description and comment ] Reviewed-by: Pratyush Yadav (Google) Reviewed-by: Samiullah Khawaja Tested-by: Samiullah Khawaja Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/gup.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index f809361227e7e..cc4fa18783ce0 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3527,6 +3527,20 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, goto err; } + /* + * fallocate() can leave folios in the + * page cache that were never cleared. + */ + if (!folio_test_uptodate(folio)) { + folio_lock(folio); + if (!folio_test_uptodate(folio)) { + folio_zero_range(folio, 0, folio_size(folio)); + flush_dcache_folio(folio); + folio_mark_uptodate(folio); + } + folio_unlock(folio); + } + if (nr_folios == 0) *offset = offset_in_folio(folio, start); -- 2.43.0