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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) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: D8A8CA000E X-Stat-Signature: mmajzhy9fwiaxjj5u5wwgrgmmoccq9zu X-HE-Tag: 1755092234-649854 X-HE-Meta: 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 ToigS0o4 uDT1ubeWYawLuRVP/uGMpG7obKjHTrv4P9u3siaXwHdoldbD9hlp5fo6nDkbY9hFLNZpoA7rl8w1l1o0G9B7vfqiG8FqY063iLFQN1iEnguTbJuGFHOJq41tlBwhgxV/0S3JoiYwLMpXT+erpo1VLx2YAtNJQSlazQmD79cRPy6p3kfRGo9bOLhqk56YNMo1PMnFe18Yo1fX4s54vEWvwC+16Mbo3ntuMjVkWnOD3tyOGfvI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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