From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 336AC2D542A; Wed, 13 Aug 2025 12:14:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755087267; cv=none; b=oKpagVfGkvbN/nEFyn7MFDQiOQ2tLNbUGw17nIymGLRMCOmAUTuG9Hk1rgf5ba3ChVztaoRQBPAT3ZW63V9zyFfqce8NMoVRm3tm7h/Pl+S6tzhJgaj6c+lTR8LCOPY+UJiCa7vXI471aUXX3vOgb4N1DRG24cmqUM+Ze+Bo7B8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755087267; c=relaxed/simple; bh=tLOV7MuxuGZuAFjpe/xUc874h2DrbSyeczMhXjDQFOI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L1Zz3YQTOvBcgvmlyoV7fO7mWB+/fELDoT8B301O3eGHOXbywcaY7YqlQQSWFj+8zlpfrQhrxj0xnnU+4Tmf3Iezk6a5ahPosAcajHZ4drGkESfEepioCEHsFHax/cYyFyL3m8SgRQPsV9pb+bbL4JGO8DkfNTsNTsu1Ymqra3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rujDt7ws; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rujDt7ws" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A10ECC4CEEB; Wed, 13 Aug 2025 12:14:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755087266; bh=tLOV7MuxuGZuAFjpe/xUc874h2DrbSyeczMhXjDQFOI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rujDt7wsKQqVTbCwQrtiVRdM2aH76LameWGzvTdZ5npEBlrG95aNQxa3fQpNRodhk QJbxh/7YOXP2RZlRsBQ3Euf+xwHlnxbyvDua1jB4H6D5yGcYFwDUM1uYw6W6cryK3z Pug/jEnZ7mb8BeSzL61ybm0Sudo+Z5LhYzcQFvOs= Date: Wed, 13 Aug 2025 14:14:23 +0200 From: Greg KH To: Pratyush Yadav Cc: Vipin Sharma , Pasha Tatashin , jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, rppt@kernel.org, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: Re: [PATCH v3 29/30] luo: allow preserving memfd Message-ID: <2025081351-tinsel-sprinkler-af77@gregkh> References: <20250807014442.3829950-1-pasha.tatashin@soleen.com> <20250807014442.3829950-30-pasha.tatashin@soleen.com> <20250813063407.GA3182745.vipinsh@google.com> <2025081310-custodian-ashamed-3104@gregkh> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Aug 13, 2025 at 02:02:07PM +0200, Pratyush Yadav wrote: > On Wed, Aug 13 2025, Greg KH wrote: > > > On Tue, Aug 12, 2025 at 11:34:37PM -0700, Vipin Sharma wrote: > >> On 2025-08-07 01:44:35, Pasha Tatashin wrote: > >> > From: Pratyush Yadav > >> > +static void memfd_luo_unpreserve_folios(const struct memfd_luo_preserved_folio *pfolios, > >> > + unsigned int nr_folios) > >> > +{ > >> > + unsigned int i; > >> > + > >> > + for (i = 0; i < nr_folios; i++) { > >> > + const struct memfd_luo_preserved_folio *pfolio = &pfolios[i]; > >> > + struct folio *folio; > >> > + > >> > + if (!pfolio->foliodesc) > >> > + continue; > >> > + > >> > + folio = pfn_folio(PRESERVED_FOLIO_PFN(pfolio->foliodesc)); > >> > + > >> > + kho_unpreserve_folio(folio); > >> > >> This one is missing WARN_ON_ONCE() similar to the one in > >> memfd_luo_preserve_folios(). > > > > So you really want to cause a machine to reboot and get a CVE issued for > > this, if it could be triggered? That's bold :) > > > > Please don't. If that can happen, handle the issue and move on, don't > > crash boxes. > > Why would a WARN() crash the machine? That is what BUG() does, not > WARN(). See 'panic_on_warn' which is enabled in a few billion Linux systems these days :(