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 178972E7F39; Wed, 13 Aug 2025 13:37:13 +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=1755092234; cv=none; b=tec0FV44bwH2pzWF9ufBGdg/qlcKmg/e66HRlZ+/FdH6UzIiyiNGomXaI+R4k6xoOQeCf5bSmnPCdehyAwlJAeZyaAkf1HlCWdQbJJSQWQPMVGfdOoVR8gtjs2rK16/PzVUNz2aK/Zgoy213jyjVg8E3xAo25v4emaS9HlD5/vs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755092234; c=relaxed/simple; bh=gKvz2MC5wozp0txCtJXl7kNfS6x4R8q1KKyu7d5k0DY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=QX9xxjBnI4ISrL0j3phNCi36A0vC6x/FrTFnCec4k8rzo5Zu6nfm7PqmSS/r1Kbjt3KHtdWnzaPz3ntli5sfz7HkyzFGcg6IDupkMWdoEE+f/jsdTJv9N1jHOPTrKsKfnGPf0x4iqopjA5W588i1jQmJmgyqlmA2k5AbvOoZQUQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pm1jF1Lj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pm1jF1Lj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75F89C4CEEB; Wed, 13 Aug 2025 13:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755092233; bh=gKvz2MC5wozp0txCtJXl7kNfS6x4R8q1KKyu7d5k0DY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=Pm1jF1Ljm5T+6BOOZNpYAiyUBhA6jrJJ3DRvXghpATFhZq9GKA5j1j8Xl9om6Mvqd pfb6YVvFxGbv9PYSjK3q5G96TXeo13NOsZZUcX4p7BOHPPWqewIaajNssSIIJq67Ir xfAz6+V7B0aTsEcI3pSfGZBQt5DjXUcnHfEh22WdBQkwWMnVlBIrcbQjMhPFgaUYB6 +kXK07xwObo+yLiDzPd/6jG/pDA9bkPmsMRnuHEkIUSaR5V081dJnNqOCzoK22kD1K S3FF/GtK8QX6tTieEmA3XosMZYGA78RfsgeODd3LX+itirXiSMrsG7A+4N9RcdACEg oreSW4Z88W6PQ== From: Pratyush Yadav To: Greg KH Cc: Jason Gunthorpe , Pratyush Yadav , 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, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: Re: [PATCH v3 29/30] luo: allow preserving memfd In-Reply-To: <2025081334-rotten-visible-517a@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> <2025081351-tinsel-sprinkler-af77@gregkh> <20250813124140.GA699432@nvidia.com> <2025081334-rotten-visible-517a@gregkh> Date: Wed, 13 Aug 2025 15:37:03 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Aug 13 2025, Greg KH wrote: > On Wed, Aug 13, 2025 at 09:41:40AM -0300, Jason Gunthorpe wrote: [...] >> Use the warn ons. Make sure they can't be triggered by userspace. Use >> them to detect corruption/malfunction in the kernel. >> >> In this case if kho_unpreserve_folio() fails in this call chain it >> means some error unwind is wrongly happening out of sequence, and we >> are now forced to leak memory. Unwind is not something that userspace >> should be controlling, so of course we want a WARN_ON here. > > "should be" is the key here. And it's not obvious from this patch if > that's true or not, which is why I mentioned it. > > I will keep bringing this up, given the HUGE number of CVEs I keep > assigning each week for when userspace hits WARN_ON() calls until that > flow starts to die out either because we don't keep adding new calls, OR > we finally fix them all. Both would be good... Out of curiosity, why is hitting a WARN_ON() considered a vulnerability? I'd guess one reason is overwhelming system console which can cause a denial of service, but what about WARN_ON_ONCE() or WARN_RATELIMIT()? -- Regards, Pratyush Yadav