From: Thomas Gleixner <tglx@linutronix.de>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>, Linux-MM <linux-mm@kvack.org>
Subject: Re: [patch V4 01/32] mm/slab: Fix broken stack trace storage
Date: Mon, 15 Apr 2019 23:20:42 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1904152318020.1806@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190415161657.2zwboghblj5ducux@treble>
On Mon, 15 Apr 2019, Josh Poimboeuf wrote:
> On Mon, Apr 15, 2019 at 06:07:44PM +0200, Thomas Gleixner wrote:
> > >
> > > Looks like stack_trace.nr_entries isn't initialized? (though this code
> > > gets eventually replaced by a later patch)
> >
> > struct initializer initialized the non mentioned fields to 0, if I'm not
> > totally mistaken.
>
> Hm, it seems you are correct. And I thought I knew C.
:)
> > > Who actually reads this stack trace? I couldn't find a consumer.
> >
> > It's stored directly in the memory pointed to by @addr and that's the freed
> > cache memory. If that is used later (UAF) then the stack trace can be
> > printed to see where it was freed.
>
> Right... but who reads it?
Indeed. I didn't check but I know that I saw that info printed at least a
decade ago. Looks like that debug magic in slab.c has seen major changes
since then.
Thanks,
tglx
next prev parent reply other threads:[~2019-04-15 21:20 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-14 15:59 [patch V3 00/32] x86: Add guard pages to exception and interrupt stacks Thomas Gleixner
2019-04-14 15:59 ` [patch V3 01/32] mm/slab: Fix broken stack trace storage Thomas Gleixner
2019-04-14 16:16 ` Andy Lutomirski
2019-04-14 16:34 ` Thomas Gleixner
2019-04-15 9:02 ` [patch V4 " Thomas Gleixner
2019-04-15 13:23 ` Josh Poimboeuf
2019-04-15 16:07 ` Thomas Gleixner
2019-04-15 16:16 ` Josh Poimboeuf
2019-04-15 17:05 ` Andy Lutomirski
2019-04-15 21:22 ` Thomas Gleixner
2019-04-16 11:37 ` Vlastimil Babka
2019-04-16 14:10 ` [patch V5 01/32] mm/slab: Remove " Thomas Gleixner
2019-04-16 15:16 ` Vlastimil Babka
2019-04-15 21:20 ` Thomas Gleixner [this message]
2019-04-15 16:21 ` [patch V4 01/32] mm/slab: Fix " Peter Zijlstra
2019-04-15 16:58 ` [patch V3 " Andy Lutomirski
2019-04-14 15:59 ` [patch V3 02/32] x86/irq/64: Limit IST stack overflow check to #DB stack Thomas Gleixner
2019-04-17 14:02 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 03/32] x86/dumpstack: Fix off-by-one errors in stack identification Thomas Gleixner
2019-04-17 14:03 ` [tip:x86/irq] " tip-bot for Andy Lutomirski
2019-04-14 15:59 ` [patch V3 04/32] x86/irq/64: Remove a hardcoded irq_stack_union access Thomas Gleixner
2019-04-17 14:03 ` [tip:x86/irq] " tip-bot for Andy Lutomirski
2019-04-14 15:59 ` [patch V3 05/32] x86/irq/64: Sanitize the top/bottom confusion Thomas Gleixner
2019-04-17 14:04 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 06/32] x86/idt: Remove unused macro SISTG Thomas Gleixner
2019-04-17 14:05 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 07/32] x86/64: Remove stale CURRENT_MASK Thomas Gleixner
2019-04-17 14:06 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 08/32] x86/exceptions: Remove unused stack defines on 32bit Thomas Gleixner
2019-04-17 14:06 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 09/32] x86/exceptions: Make IST index zero based Thomas Gleixner
2019-04-17 14:07 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 10/32] x86/cpu_entry_area: Cleanup setup functions Thomas Gleixner
2019-04-17 14:08 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 11/32] x86/exceptions: Add structs for exception stacks Thomas Gleixner
2019-04-16 18:20 ` Sean Christopherson
2019-04-17 14:08 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 12/32] x86/cpu_entry_area: Prepare for IST guard pages Thomas Gleixner
2019-04-17 14:09 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 13/32] x86/cpu_entry_area: Provide exception stack accessor Thomas Gleixner
2019-04-17 14:10 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 14/32] x86/traps: Use cpu_entry_area instead of orig_ist Thomas Gleixner
2019-04-17 14:10 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 15/32] x86/irq/64: Use cpu entry area " Thomas Gleixner
2019-04-17 14:11 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 16/32] x86/dumpstack/64: Use cpu_entry_area " Thomas Gleixner
2019-04-17 14:12 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 17/32] x86/cpu: Prepare TSS.IST setup for guard pages Thomas Gleixner
2019-04-17 14:13 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 18/32] x86/cpu: Remove orig_ist array Thomas Gleixner
2019-04-17 14:13 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 19/32] x86/exceptions: Disconnect IST index and stack order Thomas Gleixner
2019-04-17 14:14 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 20/32] x86/exceptions: Enable IST guard pages Thomas Gleixner
2019-04-17 14:15 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 21/32] x86/exceptions: Split debug IST stack Thomas Gleixner
2019-04-16 22:07 ` Sean Christopherson
2019-04-17 14:15 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 22/32] x86/dumpstack/64: Speedup in_exception_stack() Thomas Gleixner
2019-04-17 14:16 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 15:59 ` [patch V3 23/32] x86/irq/32: Define IRQ_STACK_SIZE Thomas Gleixner
2019-04-17 14:17 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 24/32] x86/irq/32: Make irq stack a character array Thomas Gleixner
2019-04-17 14:18 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 25/32] x86/irq/32: Rename hard/softirq_stack to hard/softirq_stack_ptr Thomas Gleixner
2019-04-17 14:18 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 26/32] x86/irq/64: Rename irq_stack_ptr to hardirq_stack_ptr Thomas Gleixner
2019-04-17 14:19 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 27/32] x86/irq/32: Invoke irq_ctx_init() from init_IRQ() Thomas Gleixner
2019-04-17 14:20 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 28/32] x86/irq/32: Handle irq stack allocation failure proper Thomas Gleixner
2019-04-17 14:20 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 29/32] x86/irq/64: Init hardirq_stack_ptr during CPU hotplug Thomas Gleixner
2019-04-17 14:21 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
2019-04-14 16:00 ` [patch V3 30/32] x86/irq/64: Split the IRQ stack into its own pages Thomas Gleixner
2019-04-17 14:22 ` [tip:x86/irq] " tip-bot for Andy Lutomirski
2019-04-14 16:00 ` [patch V3 31/32] x86/irq/64: Remap the IRQ stack with guard pages Thomas Gleixner
2019-04-17 14:22 ` [tip:x86/irq] " tip-bot for Andy Lutomirski
2019-04-14 16:00 ` [patch V3 32/32] x86/irq/64: Remove stack overflow debug code Thomas Gleixner
2019-04-17 14:23 ` [tip:x86/irq] " tip-bot for Thomas Gleixner
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