From: Rusty Russell <rusty@rustcorp.com.au>
To: Andy Lutomirski <luto@amacapital.net>,
Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Sebastian Lackner <sebastian@fds-team.de>,
Anish Bhatt <anish@chelsio.com>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>,
Andy Lutomirski <luto@amacapital.net>,
stable@vger.kernel.org
Subject: Re: [PATCH] x86_64, entry: Fix out of bounds read on sysenter
Date: Sat, 01 Nov 2014 12:58:55 +1030 [thread overview]
Message-ID: <874muj4pso.fsf@rustcorp.com.au> (raw)
In-Reply-To: <a27467328f7607b4f45a6c37e731c1f3e047f4a7.1414803784.git.luto@amacapital.net>
Andy Lutomirski <luto@amacapital.net> writes:
> Rusty noticed a Really Bad Bug (tm) in my NT fix. The entry code
> reads out of bounds, causing the NT fix to be unreliable. But, and
> this is much, much worse, if your stack is somehow just below the
> top of the direct map (or a hole), you read out of bounds and crash.
>
> Excerpt from the crash:
>
> [ 1.129513] RSP: 0018:ffff88001da4bf88 EFLAGS: 00010296
>
> 2b:* f7 84 24 90 00 00 00 testl $0x4000,0x90(%rsp)
>
> That read is deterministically above the top of the stack. I
> thought I even single-stepped through this code when I wrote it to
> check the offset, but I clearly screwed it up.
>
> Fixes 8c7aa698baca x86_64, entry: Filter RFLAGS.NT on entry from userspace
>
> Reported-by: Rusty Russell <rusty@ozlabs.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Tested-by: Rusty Russell <rusty@rustcorp.com.au>
Thanks for the fast response...
Rusty.
prev parent reply other threads:[~2014-11-01 2:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-01 18:49 [PATCH v4 0/2] x86_64,entry: Clear NT on entry and speed up switch_to Andy Lutomirski
2014-10-01 18:49 ` [PATCH v4 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace Andy Lutomirski
2014-10-01 19:49 ` Andy Lutomirski
2014-10-02 15:36 ` H. Peter Anvin
2014-10-06 16:42 ` H. Peter Anvin
2014-10-06 18:07 ` [tip:x86/urgent] x86_64, entry: " tip-bot for Andy Lutomirski
2014-10-01 18:49 ` [PATCH v4 2/2] x86_64: Don't save flags on context switch Andy Lutomirski
2014-10-06 16:39 ` [PATCH v4 0/2] x86_64,entry: Clear NT on entry and speed up switch_to Andy Lutomirski
2014-10-06 16:41 ` H. Peter Anvin
2014-10-06 16:45 ` Andy Lutomirski
2014-10-06 16:57 ` H. Peter Anvin
2014-11-01 0:20 ` Rusty Russell
2014-11-01 1:00 ` Andy Lutomirski
2014-11-01 1:08 ` [PATCH] x86_64, entry: Fix out of bounds read on sysenter Andy Lutomirski
2014-11-01 2:28 ` Rusty Russell [this message]
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