From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B2813C88E72 for ; Thu, 17 Sep 2026 16:54:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CE29310E740; Thu, 17 Sep 2026 16:54:09 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="eyLCjGmd"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 95F3610E740 for ; Thu, 17 Sep 2026 16:54:08 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4464943F26; Thu, 17 Sep 2026 16:54:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF3671F00893; Thu, 17 Sep 2026 16:54:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789664048; bh=soTBV+PjMnLk3CJqDep3SeaGxjjzvxEjiNUk8qBpmsU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=eyLCjGmdrDwctVmdHC7BJ3p9PF7o5gpRumDdAuDAaNy8Ld2HpjE2vuKO9qOrrRHPW BIVGQKAcpQ8Tj0OpdswMByR6ajR3Dr82AtiefkpkLRgfILf0If9zPj9JfsJLEwzHko lZ+oKPguQan3LQuuXUKVNSNNMX5mooVKrg6a07th26o4uULzeIlVKJQilArdmXeR1I hEXdXdBvG98j1Uhq6/S7vugxw7MRbvx2aNsyq2olk+tmmGC5oeXOUXad9+03EQgA/r PRR7KJN5XzZUPvjgUyDNjVHsKlxnZtkUnez9B+V0y/tkfkcJzV+ScJO0Z4Cj1IA/FQ 1fth1ZkQIXKUQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH v3 01/40] mm/vma: fix mmap_prepare file handling, remove file_doesnt_need_get To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: kvm@vger.kernel.org, selinux@vger.kernel.org, linux-scsi@vger.kernel.org, "Alexander Gordeev" , "Heiko Carstens" , "Christian Borntraeger" , "Oliver Upton" , "Marc Zyngier" , linux-s390@vger.kernel.org, "Vasily Gorbik" , linux-rdma@vger.kernel.org, kvmarm@lists.linux.dev, linux-trace-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-perf-users@vger.kernel.org, bpf@vger.kernel.org In-Reply-To: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-1-4583d8a23bca@kernel.org> References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-1-4583d8a23bca@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 17 Sep 2026 16:54:06 +0000 Message-Id: <20260917165406.DF3671F00893@smtp.kernel.org> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] mm: NULL pointer dereference in compat_vma_mmap() error and succes= s paths -- commit ed2cb69a22a3cc12d20a6c5599880de22d11566c Author: Lorenzo Stoakes (ARM) mm/vma: fix mmap_prepare file handling, remove file_doesnt_need_get =20 The map->file_doesnt_need_get flag is confusing and the existing implementation has holes. [ ... ] > diff --git a/mm/util.c b/mm/util.c > index bf0513d1d3d08..016932780925e 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -1228,8 +1228,11 @@ int __compat_vma_mmap(struct vm_area_desc *desc, > =20 > /* Perform any preparatory tasks for mmap action. */ > err =3D mmap_action_prepare(desc); > - if (err) > + if (err) { > + if (desc->vm_file !=3D vma->vm_file) > + fput(desc->vm_file); [Severity: High] Is it possible for desc->vm_file to be NULL here? If a stacked driver's mmap_prepare() hook changes the mapping to anonymous (clearing desc->vm_file to NULL) and mmap_action_prepare() fails, this error path would call fput(desc->vm_file) passing NULL. Because fput() does not tolerate NULL pointers, would this lead to a NULL pointer dereference? > return err; > + } > /* Update the VMA from the descriptor. */ > compat_set_vma_from_desc(vma, desc); > /* Complete any specified mmap actions. */ [ ... ] > diff --git a/mm/vma.h b/mm/vma.h > index e97bd2dfa786d..f15faa83f3d63 100644 > --- a/mm/vma.h > +++ b/mm/vma.h > @@ -394,8 +394,10 @@ static inline void compat_set_vma_from_desc(struct v= m_area_struct *vma, > =20 > /* Mutable fields. Populated with initial state. */ > vma_set_pgoff(vma, desc->pgoff); > - if (desc->vm_file !=3D vma->vm_file) > - vma_set_file(vma, desc->vm_file); > + if (desc->vm_file !=3D vma->vm_file) { > + fput(vma->vm_file); [Severity: High] Similarly, could vma->vm_file be NULL here? If __compat_vma_mmap() is invok= ed on an initially anonymous VMA (where vma->vm_file is NULL) and the driver provides a backing file, this success path calls fput(vma->vm_file) passing NULL. > + vma->vm_file =3D desc->vm_file; > + } > vma->flags =3D desc->vma_flags; > vma->vm_page_prot =3D desc->page_prot; > --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260917-b4-mmap-pr= epare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org?part=3D1