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=1793807873; b=Fi3JOOs8VKzhF9/zAAEblv4qD1HIh28ewSxEwDeSG6S89QugxNWBrrjRPpHhyMEH/CgZ YYPgDK5kQ67tHy83kKbt8ZFivACMl3Q2G6a25GuIVrYdo7HlJEROd7UlN+Cgn7AoWRw4X AXY6xaGN7g1nOrwQ8S8+7HhXvmj2R3CVrAobg89YJEqNxZqANWt7uDDQGdDPFfaG2BExb 5rZWX5sZ7DzvaCKg4iaNWR7TWqtkQzpseiUoNygkHYUXOsjYF/Kx6CIrQ54Sg1Z+8rYzL MXNHs7zNlEQwcJOm8jkEg3XCQYB5vZsnBYI6YUjs/R8AtjrKL2s1owDj5xlGlWrFyRg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793807873; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=PjKfK9lFpy8OfPJsRfQH6HcluTUTVSvczIy7XWdUbDs=; b=trJz4XlpOPBY82ASvfE+hoY8i8eagCo5jxATBONfy9fTT1NjrKZllyYza/k4/LGorS87 zmMIwlFx3otPdGblXvfAofh1kB8H0OCo+BrxL59K9NdXnWgdS31MsboWYFb9VJ52hyGqL uXZSCT0V3Th8uIZMNJSGpV+KUlMzhPLeQOUlxN14FEyn+1sTPxxK93COmxY59op7rTSDL kIR5to0/F6UscbKVsgUJ1Xm/6wdK5vDO1g6EpQNgwFNoJk3QaaPyHqw6JBHxw5oJb0Aq9 k8ne38TslmGgN5OanFVsUIAiHBcy00qU1mQjx7WSUQeNSRtKY6inpGsqBmBghAWFb4Q== 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=OM4+o8lU; 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 7FE556082BC1 for ; Wed, 4 Nov 2026 15:57:53 +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=OM4+o8lU Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23ADC1F00A1B; Wed, 4 Nov 2026 15:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793807873; bh=PjKfK9lFpy8OfPJsRfQH6HcluTUTVSvczIy7XWdUbDs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OM4+o8lUpuXN7sIk2JZajFny5tyZe73jrJTzXEJYusMa7fZZ+iO21Rl7LJIwOC3NQ NW+ATF2ozQ7vxda5etYnJEu/JPUTrX8WQOFNmWNPa2d8J0B5JUKJScpqhs/Lc0UNBN uKT2uuMBVIxngkJpXDIAhE2IqYAD7QGeIy9e4ASyeDr8/TIxZ+5xAtIONrzW76Vfnb t749k0FYa97Ig2HWl29Br93NJee48f9DFegZNIdOl8o4E1gvqbotMXpSnEOk9Z6woP vxKlRtN/eYlnoELWBEAYWZ8jodfoHXVtuYQvosCnJX0N3HPMOM5vBPdc/MMvLG7Hlc L4mvte3+2QXow== From: Sasha Levin To: stable@vger.kernel.org Cc: "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 , Sasha Levin Subject: [PATCH 6.1.y] mm/hugetlb: fix use-after-free in hugetlb_mfill_atomic_pte() Date: Wed, 4 Nov 2026 10:57:49 -0500 Message-ID: <20261104155729.3920030-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110446-swimmer-stimulate-cc19@gregkh> References: <2026110446-swimmer-stimulate-cc19@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "David Hildenbrand (Arm)" [ Upstream commit d8a9cd7fd2fb01211430c933932da58839b8ca65 ] 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: [ sashal: Adapted folio operations to the existing struct page API in hugetlb_mcopy_atomic_pte(). ] Signed-off-by: Sasha Levin --- mm/hugetlb.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index fc26639f87dc5..de805b385d06b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6428,11 +6428,16 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); - spin_unlock(ptl); if (!is_continue) SetHPageMigratable(page); if (vm_shared || is_continue) unlock_page(page); + + /* + * Hold the PTL until we're done with the page: the page table owns the + * page reference now. + */ + spin_unlock(ptl); ret = 0; out: return ret; -- 2.53.0