From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EEAF62F7F18 for ; Wed, 27 May 2026 18:48:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779907686; cv=none; b=bFLx6aVqsFvPUmI4CbKlZ5uaYHKvxeDHCGCtVf6sUhTtawPFg5DErDdj8BciiB/99JueyMTbdiyXingyxx+xbCEVXz+YIq26+5T2JJLcYJz7nX2atfeJM/Zd35XmW0P7xUq0Eoq02sD5hCRRHVCc3IkfgJ+erO0bgrS0WoRzLGY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779907686; c=relaxed/simple; bh=yAIrwa4E1hakK2iMBSw2aOMZzmR2OGKXwNNjWcIHMIQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E5+IJz4Gzp1fylBcnud8xINZWsnMZmxSpwpEVKDsZwTT0mrmjwmDV1clSOeNC6pZ70JQJhs2bGG9A7gwsiPmTGgG4O+p8geYwbzbOJEN5eMKuuxALgU2r+jBAZRZPgZmUnlewGyrKt/xjlC8oyYZitDjl2nKo/81IpS3kk61q60= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kRoX7yVU; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kRoX7yVU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E818E1F000E9; Wed, 27 May 2026 18:48:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779907684; bh=dRSYO9/9bR0VX2Or4HoVo4m/cqxBZNmu+Ypk7OqiXPg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kRoX7yVUnMQec8ELSRsqOSyrWPmRFWm7oaNBr1RunHRiYkJHwdhXT5uoI65FaoN5Y gzZbvEahTLDAyoPjZtjtRSTQ8zLOi4QfP43lSm2BZNvvIqc3CSmKRyNtuxI4J2cIz5 uMBXfXKV9xWlkR3LnSITJJrCH7OtzVvJe4aWMmP4EhxeIDBf61g/f7OZ/zrcguyrOp XLPylXlGh106yhi8JWllMWWVYSjjprsp6UszlhijGbptAYcQOgBK2M8XMln9r51nKh KVM5zemZT8bUdHY+M9EoKmx/gKtXrgHIrYZAR6PRCqDENbi8lv23dFDSbZ+nYcR6TP KZvgchARk1NYA== From: Mike Rapoport To: Andrew Morton Cc: David Carlier , David Hildenbrand , Heechan Kang , "Liam R. Howlett" , Lorenzo Stoakes , Michael Bommarito , Mike Rapoport , Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/3] userfaultfd: refuse to __mfill_atomic_pte() for unsupported VMAs Date: Wed, 27 May 2026 21:47:50 +0300 Message-ID: <20260527184751.4147364-3-rppt@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260527184751.4147364-1-rppt@kernel.org> References: <20260527184751.4147364-1-rppt@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Mike Rapoport (Microsoft)" __mfill_atomic_pte() unconditionally dereferences ops because there is an assumption that VMAs that can undergo mfill_* operations are vetted on registration and must have valid vm_uffd_ops. Add a guard against potential bugs and make sure __mfill_atomic_pte() bails out if ops is NULL. Suggested-by: Lorenzo Stoakes Fixes: ad9ac3081332 ("userfaultfd: introduce vm_uffd_ops->alloc_folio()") Signed-off-by: Mike Rapoport (Microsoft) --- mm/userfaultfd.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index e5d2fb3ce2c1..2872c71bbf36 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -552,6 +552,11 @@ static int __mfill_atomic_pte(struct mfill_state *state, struct folio *folio; int ret; + if (!ops) { + VM_WARN_ONCE(1, "UFFDIO_COPY for unsupported VMA"); + return -EOPNOTSUPP; + } + folio = ops->alloc_folio(state->vma, state->dst_addr); if (!folio) return -ENOMEM; -- 2.53.0