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Mon, 7 Sep 2026 12:59:58 +0000 Message-ID: Date: Mon, 7 Sep 2026 14:59:54 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/3] drm/sched: cache the timeline name to fix a use-after-free To: phasta@kernel.org, Tvrtko Ursulin , "Jonghyuk Kim(MalHyuk)" , matthew.brost@intel.com, dakr@kernel.org Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, mdaenzer@redhat.com, alessio.belle@imgtec.com, luigi.santivetti@imgtec.com, stable@vger.kernel.org References: <20260904080618.2098450-1-malhyuk97@gmail.com> <20260904080618.2098450-2-malhyuk97@gmail.com> <7e4497506bb051fd1c25ed54f88a8036084e779c.camel@mailbox.org> <81e51d72-d608-46d0-a986-390ecd6f468a@ursulin.net> <47464619-890d-484f-986b-9a6c06cd89b0@ursulin.net> <2aa58eb8-a33f-45b9-8ee0-518d72160f41@ursulin.net> <206df2dad0c68b8c25862c74c0a8399940044af2.camel@mailbox.org> Content-Language: en-US From: =?UTF-8?Q?Christian_K=C3=B6nig?= In-Reply-To: <206df2dad0c68b8c25862c74c0a8399940044af2.camel@mailbox.org> Content-Type: text/plain; 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In that "world" it would have been safe. Did 035219a760ed >> ("dma-buf: dma-fence: Fix potential NULL pointer dereference") break >> those fixes a bit? > > I think we all agree that 035219a760ed should not have been implemented > in that way because it does not work for drivers that provide a ops- >> release / ops->wait. > > So I think the only thing we can do right now is add the signaled-check > back (like Christian suggested) and ensure correct memory ordering – > since we also cannot use the spinlock consistently, as that can still > be extern… I think the memory ordering isn't really a problem. See if the ops pointer or the signaled bit is loaded first doesn't matter if you check both. You only need to make sure that the ops pointer is loaded once cause that one is used multiple times, but that is already the case by using rcu_dereference(). Or what exactly is your concern? Thanks, Christian. > > > P.