From: Vince Weaver <vincent.weaver@maine.edu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H.J. Lu" <hjl.tools@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: perf_fuzzer compiled for x32 causes reboot
Date: Mon, 24 Feb 2014 12:32:39 -0500 (EST) [thread overview]
Message-ID: <alpine.DEB.2.10.1402241230440.20170@vincent-weaver-1.um.maine.edu> (raw)
In-Reply-To: <20140224172536.GD9987@twins.programming.kicks-ass.net>
On Mon, 24 Feb 2014, Peter Zijlstra wrote:
> On Mon, Feb 24, 2014 at 12:10:44PM -0500, Vince Weaver wrote:
> > On Mon, 24 Feb 2014, H. Peter Anvin wrote:
> >
> > > On February 24, 2014 8:34:30 AM PST, Vince Weaver <vincent.weaver@maine.edu> wrote:
> > > >On Mon, 24 Feb 2014, Vince Weaver wrote:
> > > >
> > > >> Just touching the mmap page with a write of a single byte (it doesn't
> > > >
> > > >> matter where) is enough to trigger the bug.
> > > >
> > > >OK, investigating this more.
> > > >
> > > >perf_fuzzer-2971 [000] 154.944114: page_fault_user:
> > > >address=0xf7729000 ip=0x41efab error_code=0x6
> > > >perf_fuzzer-2971 [000] 154.944118: function:
> > > >ip=0xffffffff810d40e7 parent_ip=0xffffffff810d0840
> > > >perf_fuzzer-2971 [000] 154.944119: function:
> > > >ip=0xffffffff812a91a5 parent_ip=0xffffffff81013ff5
> > > >perf_fuzzer-2971 [000] 154.944120: function:
> > > >ip=0xffffffff8153837c parent_ip=0xffffffff81535432
> > > >perf_fuzzer-2971 [000] 154.944121: page_fault_kernel:
> > > >address=0x22e0 ip=0xffffffff812a7d5c error_code=0x0
> >
> > > Ok, so the obvious question is what is at that kernel address?
> > >
> >
> > It's in copy_user_generic_string()
> > rep movsq %ds:(%rsi),%es:(%rdi)
> >
> > And looking at the ftrace:
> > perf_fuzzer-2979 [000] 161.475920: page_fault_user: address=__per_cpu_end ip=__per_cpu_end error_code=0x6
> > perf_fuzzer-2979 [000] 161.475922: function: perf_callchain
> > perf_fuzzer-2979 [000] 161.475922: function: copy_from_user_nmi
> > perf_fuzzer-2979 [000] 161.475923: function: trace_do_page_fault
> > perf_fuzzer-2979 [000] 161.475924: page_fault_kernel: address=irq_stack_union ip=copy_user_generic_string error_code=0x0
> >
> > What is likely happening is the user page fault is triggering
> > code to do a "perf_callchain" dump, which is calling copy_from_user_nmi()
> > which calls copy_user_generic_string() which is somehow getting the user
> > RBP in the RDI register somehow?
>
> So that code very much relies on the 'recursive' NMI/iret magic from
> Steve, patch 3f3c8b8c4b2a3 (and assorted fixes later).
>
> If CR2 is getting corrupted; 7fbb98c5cb075 seems relevant.
>
> Peter, does x32 have a slightly different ABI/calling convention that
> would make any of these patches just slightly 'off'?
I do note that
perf_callchain_user();
Does
fp = (void __user *)regs->bp;
...
bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
And in my particular executable RBP has nothing to do with a frame
pointer, but is instead being used as a general purpose register.
Am I missing something here? Though in that case I'm not sure why this
wouldn't be easier to trigger.
Vince
next prev parent reply other threads:[~2014-02-24 17:30 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-21 20:25 perf_fuzzer causes reboot Vince Weaver
2014-02-21 22:13 ` perf_fuzzer compiled for x32 " Vince Weaver
2014-02-21 22:34 ` Vince Weaver
2014-02-22 4:50 ` Vince Weaver
2014-02-22 5:03 ` H. Peter Anvin
2014-02-22 6:26 ` H. Peter Anvin
2014-02-23 5:18 ` Vince Weaver
2014-02-23 5:24 ` H. Peter Anvin
2014-02-23 6:07 ` H. Peter Anvin
2014-02-23 14:05 ` Vince Weaver
2014-02-24 3:02 ` Vince Weaver
2014-02-24 5:22 ` H. Peter Anvin
2014-02-24 15:35 ` Vince Weaver
2014-02-24 16:34 ` Vince Weaver
2014-02-24 16:47 ` H. Peter Anvin
2014-02-24 17:10 ` Vince Weaver
2014-02-24 17:25 ` Peter Zijlstra
2014-02-24 17:32 ` Vince Weaver [this message]
2014-02-24 17:40 ` H. Peter Anvin
2014-02-24 18:00 ` Vince Weaver
2014-02-24 18:07 ` Vince Weaver
2014-02-24 18:34 ` H. Peter Anvin
2014-02-24 19:13 ` Steven Rostedt
2014-02-24 19:15 ` H. Peter Anvin
2014-02-24 19:30 ` Peter Zijlstra
2014-02-24 19:32 ` Steven Rostedt
2014-02-25 3:49 ` H. Peter Anvin
2014-02-25 14:07 ` Vince Weaver
2014-02-25 14:34 ` H. Peter Anvin
2014-02-25 14:43 ` Steven Rostedt
2014-02-25 15:33 ` Vince Weaver
2014-02-26 15:06 ` Vince Weaver
2014-02-27 22:06 ` Vince Weaver
2014-02-27 22:31 ` Steven Rostedt
2014-02-27 22:52 ` H. Peter Anvin
2014-02-27 23:30 ` Steven Rostedt
2014-02-27 23:46 ` H. Peter Anvin
2014-02-28 1:00 ` Vince Weaver
2014-02-28 20:34 ` Paul E. McKenney
2014-02-28 20:47 ` Steven Rostedt
2014-02-28 20:54 ` Peter Zijlstra
2014-02-28 21:17 ` Paul E. McKenney
2014-02-28 21:27 ` Peter Zijlstra
2014-02-28 21:51 ` Paul E. McKenney
2014-02-28 21:55 ` Peter Zijlstra
2014-02-28 22:05 ` Steven Rostedt
2014-02-28 22:23 ` Paul E. McKenney
2014-02-28 1:34 ` Vince Weaver
2014-02-28 2:17 ` H. Peter Anvin
2014-02-28 2:57 ` Steven Rostedt
2014-02-28 11:11 ` Peter Zijlstra
2014-02-28 13:37 ` Steven Rostedt
2014-02-28 14:15 ` Vince Weaver
2014-02-28 14:23 ` Steven Rostedt
2014-02-28 15:07 ` Vince Weaver
2014-02-28 15:13 ` H. Peter Anvin
2014-02-28 15:40 ` Peter Zijlstra
2014-02-28 16:15 ` H. Peter Anvin
2014-02-28 16:29 ` Steven Rostedt
2014-02-28 19:33 ` [PATCH] x86: Rename copy_from_user_nmi() to copy_from_user_trace() Steven Rostedt
2014-02-28 20:46 ` Peter Zijlstra
2014-02-28 20:51 ` Steven Rostedt
2014-02-28 20:58 ` Peter Zijlstra
2014-02-28 21:01 ` Steven Rostedt
2014-02-28 21:17 ` Peter Zijlstra
2014-02-28 20:56 ` perf_fuzzer compiled for x32 causes reboot Peter Zijlstra
2014-02-28 21:06 ` Steven Rostedt
2014-03-01 9:16 ` Ingo Molnar
2014-03-01 9:50 ` Borislav Petkov
2014-03-01 16:50 ` H. Peter Anvin
2014-03-04 23:05 ` Borislav Petkov
2014-03-03 9:16 ` Peter Zijlstra
2014-02-28 20:55 ` Peter Zijlstra
2014-02-28 15:20 ` Steven Rostedt
2014-02-28 15:30 ` Steven Rostedt
2014-02-28 20:38 ` H. Peter Anvin
2014-02-28 20:46 ` Steven Rostedt
2014-02-28 21:18 ` Vince Weaver
2014-02-28 21:30 ` Steven Rostedt
2014-02-28 23:34 ` Vince Weaver
2014-03-01 0:43 ` H. Peter Anvin
2014-03-01 3:36 ` Steven Rostedt
2014-03-01 16:24 ` Andi Kleen
2014-03-02 15:34 ` Vince Weaver
2014-03-02 16:02 ` Vince Weaver
2014-02-28 9:39 ` Peter Zijlstra
2014-02-24 17:40 ` Peter Zijlstra
2014-02-24 17:41 ` Vince Weaver
2014-02-24 17:42 ` H. Peter Anvin
2014-02-24 17:52 ` H. Peter Anvin
2014-02-28 15:33 [PATCH] x86 trace: Fix page fault tracing bug Jiri Olsa
2014-02-28 15:47 ` Peter Zijlstra
2014-02-28 16:05 ` [PATCHv2] " Jiri Olsa
2014-02-28 16:11 ` H. Peter Anvin
2014-02-28 16:23 ` Steven Rostedt
2014-02-28 16:15 ` Steven Rostedt
2014-03-05 0:03 ` [tip:x86/urgent] x86, trace: Fix CR2 corruption when tracing page faults tip-bot for Jiri Olsa
2014-03-05 11:14 ` Peter Zijlstra
2014-03-05 12:20 ` Steven Rostedt
2014-03-05 12:25 ` Peter Zijlstra
2014-03-05 12:33 ` Steven Rostedt
2014-03-05 12:54 ` Peter Zijlstra
2014-03-05 13:02 ` Peter Zijlstra
2014-03-05 13:07 ` Peter Zijlstra
2014-03-05 12:36 ` Peter Zijlstra
2014-03-05 13:00 ` Steven Rostedt
2014-03-05 13:08 ` Peter Zijlstra
2014-03-05 21:37 ` H. Peter Anvin
2014-03-06 8:40 ` Peter Zijlstra
2014-03-06 11:02 ` Steven Rostedt
2014-03-06 14:53 ` [PATCH] x86: Further robustify CR2 handling vs tracing Peter Zijlstra
2014-03-07 23:07 ` [tip:x86/urgent] x86, trace: " tip-bot for Peter Zijlstra
2014-02-28 15:47 ` [PATCH] x86 trace: Fix page fault tracing bug Jiri Olsa
2014-02-28 16:00 ` Steven Rostedt
2014-02-28 16:01 ` Steven Rostedt
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