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=1793831462; b=cnB3BDF/oN5Dvyup7rrD2B1m5V7t7XQdnWrh3u3FZ/LUohpl3/8PYTttB0eKyj8nch6a OwLUcauDH4/O5yGeq1XuJrnVjJj1T4XOYS61ZK7hWxl5feq43N+F6mzbswPv+nDn003/+ HMp9kTSlX6/RU4Cq97Poi33M4uQAMeCZGiH0Ff5beAVrMYGzel6UjrFxDk/ygb/BMpl0M I+PZpWm7iFw/EaebGJlxmhaNQEKgGA1iHeUcg7fkMg2E7krhiBI0dzKWF7s2Hmy00XNgm 9Ts5PVKfxhR6DESyc0COlXnmTSVFJ/bXuDxjbDKxFRN2PlDD2S3Hg3tlLmlJepaEfUA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831462; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=nzE9Ojf9HlWbuLpPd6Yu1v7wJBLw/jgqNygUWkZCF7s=; b=1Qgj/f9wKeYuiTKfFIBSCgLjZR+4FH5O/6pQcKz8RkkSAoE6Mbv1ZjAOwa0kbmAZ5o65 8FdaqOcFdsRlWkriCrfnXLsNdF787gDMzVHP1S205iPcnH3dpk0IG/bNaFq0va8FveeQr FXSAJFJjy7gJsLfMY3JzPSZB8QzwuC3vqSut50qdR6z4zPb+IuT15btx6xlvx5MPagKly SYPmI8KFWeigjuq5EyiyDBrFUjuPgICxlygGGoIAB2fE6HC6OWW8YkTTyUIEQQkW1iHhO 5hkw+niVcOefWe2K/H8tnD/17Y8NNid5uqr0lxsjXo0GgERqb2DAXWDsM1h9Q7qqoUA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JttlHI+a; 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 DDC1D606A335; Wed, 4 Nov 2026 22:31:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=JttlHI+a Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63E3D1F00919; Wed, 4 Nov 2026 22:31:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831461; bh=nzE9Ojf9HlWbuLpPd6Yu1v7wJBLw/jgqNygUWkZCF7s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JttlHI+aj1lsYUHlMnPvNawtSngMhHBm07NpJOxSoTzBG32nGCqAofeplRniFAPvm 51wmedT4jFoAIz2q52is0dNMECA86+VP1bMz4v+lBUgYPga7n2M0Zd08C3IH/jc/e3 K0us045Ogceukb1MRGctaTn0cqI5IivugGnbzN4A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "David Hildenbrand (Arm)" , Andrew Morton , "Lorenzo Stoakes (ARM)" , Muchun Song , Lance Yang , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Oscar Salvador , Miaohe Lin , Naoya Horiguchi , Adam Litke , Mel Gorman , Rik van Riel , Peter Xu , Kiryl Shutsemau , Mike Rapoport , Josef Bacik Subject: [PATCH 6.18 0678/1005] mm/hugetlb: fix use-after-free in hugetlb_mfill_atomic_pte() Date: Wed, 4 Nov 2026 16:06:51 -0500 Message-ID: <20261104211102.626589584@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand (Arm) commit d8a9cd7fd2fb01211430c933932da58839b8ca65 upstream. Let's fix another instance where we use a folio after dropping the PTL, where someone else could e.g., MADV_DONTNEED it once we drop the PTL, making us trigger a use-after-free on the folio. Link: https://lore.kernel.org/20261015-urgent_fixes-v1-3-42796911043b@kernel.org Fixes: cb6acd01e2e4 ("hugetlbfs: fix races and page leaks during migration") Fixes: 1c9e8def43a3 ("userfaultfd: hugetlbfs: add UFFDIO_COPY support for shared mappings") Signed-off-by: David Hildenbrand (Arm) Signed-off-by: Andrew Morton Reported-by: Lorenzo Stoakes (ARM) Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: Muchun Song Reviewed-by: Lance Yang Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Jann Horn Cc: Pedro Falcato Cc: Oscar Salvador Cc: Miaohe Lin Cc: Naoya Horiguchi Cc: Adam Litke Cc: Mel Gorman Cc: Rik van Riel Cc: Peter Xu Cc: Kiryl Shutsemau Cc: Mike Rapoport Cc: Josef Bacik Cc: Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -7106,11 +7106,16 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_ /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); - spin_unlock(ptl); if (!is_continue) folio_set_hugetlb_migratable(folio); if (vm_shared || is_continue) folio_unlock(folio); + + /* + * Hold the PTL until we're done with the folio: the page table owns the + * folio reference now. + */ + spin_unlock(ptl); ret = 0; out: return ret;