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=1793821027; b=5F0Bw4Q2OjVHm1Kr9txXxTe/g8lLQhqCknpgoNFEIfH8QPrM5whdBiLa1Jlj/wgCUY20 QQKQYqGt6J9BnzzKPx3VfbVc3gE8JFamercL9dMkhS3xU8ECjCXnPmQpy8VbcE6UHFwlv mxNXCyRm0dXDr1LYkjvSINw7yh0FZIX0oHLgPSIHirqLPPMEsey7myOXPd5eAtsztSR3j rs7kTL4U7HDd3TrTlhS17iqpLYXZSqae5gGHxF8Z8cU5TZdyfl22wWFXd8IRUhgQ4+wx2 R0JeY402xkgpzz9ilhpnkO1cRYrk5mwu+0K4LlfKZWmMHblxRcjBrslGUkYthds8E6A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793821027; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=hYCIJyyhNvNUexJjlwv2my3b5F/WENWDx79yHOyBGJU=; b=V1LpH+CgV5GRD1xmRZ41w/PvSqUEBTc5RHKRpNr2TMw0QZx+4Gi6YS0WjKlDxj10Qmi8 2SctHqeS02X94zi73Hgr2Ricmt2kIhQw7U4X6aPRhHHRS3+TPiyUizIukbD+Lz22nJVwE KrvzNj+l6QnjETYqrheRYBV0IqtHHn4lk12nR5AQKuRlLm5m2gdHumhqwgG5x7NTjVavW K4laOdZvwL37nJcwCWfcBM/36cRAwYIT/TEbaoA80Q4bqI78G2EbdjIjuot7PfVsLx1/9 ZlpkhQZxARoqkIWVu1jESZUiLT50efPUB7RaHUm78jKCt1gvs3SrlHUSoTxyTJBNQDQ== 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="Sph9PBq/"; 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 C1F486070E77 for ; Wed, 4 Nov 2026 19:37:06 +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=Sph9PBq/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8223C1F0093A; Wed, 4 Nov 2026 19:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793821026; bh=hYCIJyyhNvNUexJjlwv2my3b5F/WENWDx79yHOyBGJU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Sph9PBq/25VUtg4Mq7AftOaKIlI5fvKekGLhjzTu1aIemGuwUBCCukqLKp0zDCoWB APLifqUDkZtWMH6/XFRNZkpu+lbLlJHaXY9RUCItKBmI9ePK0YTkc7Za0YyJtiOwIh dV8DE4jmbHqhBApdGDQSuvJChVvcCQuHaVjEvFgPbAUGd5j8EjzJNwzMOTjoE+wPVr Vgm3VPpPPxd3o9CgMFPCZgs+7mieevI267Fi0G8veIs6DWHwEjKlaZfTGzVl0i9lDZ eBay41eNiy/0PgNxSq1EEiSYd3V84a+GUP+KuvfAUL9D177UhdZ/Z2ycJ8jjuC9frn DE0IDWeJ/VwhA== 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 5.15.y] mm/hugetlb: fix use-after-free in hugetlb_mfill_atomic_pte() Date: Wed, 4 Nov 2026 14:37:03 -0500 Message-ID: <20261104193642.3970538-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110447-cucumber-tummy-2f42@gregkh> References: <2026110447-cucumber-tummy-2f42@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-based code and comments to page-based APIs 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 947610e37a33c..e8ee7ef7fe03b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5390,11 +5390,16 @@ 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