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References: <20170824175029.76040-1-ebiggers3@gmail.com> <43bcad51-b210-c1fa-c729-471fe008ba61@linux.intel.com>
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 24 Aug 2017 11:39:07 -0700
Message-ID: <CA+55aFw6zfaM=LubJnsERYVtaSdvNtGfFNRxeHvC=hahrh6wVA@mail.gmail.com>
Subject: Re: [PATCH] x86/mm: fix use-after-free of ldt_struct
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Sender: owner-linux-mm@kvack.org
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To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>, the arch/x86 maintainers <x86@kernel.org>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Eric Biggers <ebiggers@google.com>, Andrew Morton <akpm@linux-foundation.org>, Andy Lutomirski <luto@amacapital.net>, Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>, Christoph Hellwig <hch@lst.de>, Denys Vlasenko <dvlasenk@redhat.com>, Dmitry Vyukov <dvyukov@google.com>, "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>, Michal Hocko <mhocko@suse.com>, Peter Zijlstra <peterz@infradead.org>, Rik van Riel <riel@redhat.com>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Thomas Gleixner <tglx@linutronix.de>, stable <stable@vger.kernel.org>

Ingo,

 I'm assuming I get this through the -tip tree, which is where the
original commit 39a0526fb3f7 ("x86/mm: Factor out LDT init from
context init") came from.

                    Linus

On Thu, Aug 24, 2017 at 10:59 AM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
> On 08/24/2017 10:50 AM, Eric Biggers wrote:
>> --- a/arch/x86/include/asm/mmu_context.h
>> +++ b/arch/x86/include/asm/mmu_context.h
>> @@ -148,9 +148,7 @@ static inline int init_new_context(struct task_struct *tsk,
>>               mm->context.execute_only_pkey = -1;
>>       }
>>       #endif
>> -     init_new_context_ldt(tsk, mm);
>> -
>> -     return 0;
>> +     return init_new_context_ldt(tsk, mm);
>>  }
>
> Sheesh.  That was silly.  Thanks for finding and fixing this!  Feel free
> to add my ack on it.

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