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Message-ID: <20171205183845.GO3165@worktop.lehotels.local> Date: Tue, 5 Dec 2017 19:38:45 +0100 From: Peter Zijlstra <peterz@...radead.org> To: Borislav Petkov <bp@...e.de> Cc: Thomas Gleixner <tglx@...utronix.de>, qiaowei.ren@...el.com, luto@...nel.org, adam.buchbinder@...il.com, mst@...hat.com, mhiramat@...nel.org, dave.hansen@...ux.intel.com, mingo@...nel.org, linux-kernel@...r.kernel.org, colin.king@...onical.com, jslaby@...e.cz, pbonzini@...hat.com, cmetcalf@...lanox.com, akpm@...ux-foundation.org, vbabka@...e.cz, acme@...hat.com, brgerst@...il.com, shuah@...nel.org, paul.gortmaker@...driver.com, lstoakes@...il.com, hpa@...or.com, thgarnie@...gle.com, keescook@...omium.org, adrian.hunter@...el.com, ricardo.neri-calderon@...ux.intel.com, ray.huang@....com, dvyukov@...gle.com, ravi.v.shankar@...el.com, slaoub@...il.com, corbet@....net, linux-tip-commits@...r.kernel.org Subject: Re: [tip:x86/mpx] x86/insn-eval: Add utility function to get segment descriptor On Tue, Dec 05, 2017 at 07:14:56PM +0100, Borislav Petkov wrote: > On Tue, Dec 05, 2017 at 06:48:44PM +0100, Peter Zijlstra wrote: > > This is broken right? You unlock and then return @desc, which afaict can > > at that point get freed by free_ldt_struct(). > > > > Something like the below ought to cure; although its not entirely > > pretty either. > > Right. > > Or, instead of introducing all the locking, we could also not do > anything because all that code runs inside fixup_umip_exception() so the > desc will be valid there. Sorry what? So either this code is broken because it has IRQs enabled, or its broken because its trying to acquire a mutex with IRQs disabled. Which is it?
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