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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2b/I8Q8CtrPTb9BsmMkVcw4Xk5xZ+oMPIBMOH5Ta9weUZ+2KnKkWk7qgi2m4uCduj WjJ//hLYdGC8LtH/h9D7XDYUGmxoF8P2lrecXPH2EHat2C7eRwX8Y4UFcHDH/LxUPf o38cQmCkR1Y2kcyKbUMjSZhbFEAx8hiFx9X/LXOI= Date: Wed, 13 Aug 2025 15:53:28 +0200 From: Greg KH To: Pratyush Yadav Cc: Jason Gunthorpe , 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 Message-ID: <2025081338-dingo-oyster-bbbb@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 566E54000B X-Stat-Signature: s693eatpy4srxtah5ynq9jy6myi5xi6d X-Rspam-User: X-HE-Tag: 1755093213-89435 X-HE-Meta: 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 9MWBTcEY veevI0JFg97OScEIjeIDK4xDYdf2oB26ouHRJBUIvVzhC5WQSHZJVTVj3NnaWYMDEZWgSzg5J5yakhf4LDqNEXHPKEn4GdncWgDd9JbqLiaiUzoZWLDgjjnNbz17pua2+utWcm1Px07NTBfTleDMNDgK4/yleRdX8o53EUw60K52N1NqDH/3agTq/iJjm42bjrBE59SlfqMIpgHU90OBHKDpvGMtvXHCH6+4G+Eq3DApsFZBJtrMP29lh5aweqeFPEIAGLk8Yexpst+o7EvyLWiLV+D73Xly5QO9CMj1kfis2tO0ouIihYAzSNkysrHNGm9r9GnPHd/Xr+PA2XOr/lzlc2CTsi7Qdq7q6zfZ0weJz0E05grGUgaAP6vmDmsrNU/Aa29geAlz5pimJgrDzC/ohGjFMqEUP5SYhVJnXBXdSh6W897Pht6OlWzCfsC1VrKgV 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 at 03:37:03PM +0200, Pratyush Yadav wrote: > 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()? If panic_on_warn is set, this will cause the machine to crash/reboot, which is considered a "vulnerability" by the CVE.org definition. If a user can trigger this, it gets a CVE assigned to it. hope this helps, greg k-h