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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 02/21] x86/unwinder: Handle stack overflows more gracefully
Date: Mon, 27 Nov 2017 22:55:16 -0600	[thread overview]
Message-ID: <20171128045516.almy3bve5qafb6bk@treble> (raw)
In-Reply-To: <20171127173604.eff4ta576mpxjhjg@pd.tnic>

On Mon, Nov 27, 2017 at 06:36:04PM +0100, Borislav Petkov wrote:
> > +static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr,
> > +				  unsigned long *ip, unsigned long *sp)
> > +{
> > +	struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET;
> 
> I guess those are traditionally done with container_of()...

Without modifying pt_regs, there's no container to speak of, but at
least IRET_FRAME_OFFSET uses offsetof(), which is similar.

> But yeah, FWIW, looks ok to me:
> 
> Reviewed-by: Borislav Petkov <bp@suse.de>

Thanks!


Ingo, can you fold in the below changes based on Boris' comments?


diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 5be2fb23825a..c1688c2d0a12 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -57,7 +57,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 #if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
 /*
  * WARNING: The entire pt_regs may not be safe to dereference.  In some cases,
- * only the iret registers are accessible.  Use with caution!
+ * only the iret frame registers are accessible.  Use with caution!
  */
 static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
 {
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index fc918744ad7d..0bc95be5c638 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -66,7 +66,7 @@ static void show_regs_safe(struct stack_info *info, struct pt_regs *regs)
 		/*
 		 * When an interrupt or exception occurs in entry code, the
 		 * full pt_regs might not have been saved yet.  In that case
-		 * just print the iret return frame.
+		 * just print the iret frame.
 		 */
 		show_iret_regs(regs);
 	}

  reply	other threads:[~2017-11-28  4:55 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27 10:45 [PATCH 00/21] Preparatory patches for x86 KAISER support Ingo Molnar
2017-11-27 10:45 ` [PATCH 01/21] x86/unwinder/orc: Don't bail on stack overflow Ingo Molnar
2017-11-27 14:47   ` Borislav Petkov
2017-11-27 10:45 ` [PATCH 02/21] x86/unwinder: Handle stack overflows more gracefully Ingo Molnar
2017-11-27 17:36   ` Borislav Petkov
2017-11-28  4:55     ` Josh Poimboeuf [this message]
2017-11-27 10:45 ` [PATCH 03/21] x86/irq: Remove an old outdated comment about context tracking races Ingo Molnar
2017-11-27 10:45 ` [PATCH 04/21] x86/irq/64: Print the offending IP in the stack overflow warning Ingo Molnar
2017-11-27 10:45 ` [PATCH 05/21] x86/entry/64: Allocate and enable the SYSENTER stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 06/21] x86/dumpstack: Add get_stack_info() support for " Ingo Molnar
2017-11-27 10:45 ` [PATCH 07/21] x86/entry/gdt: Put per-CPU GDT remaps in ascending order Ingo Molnar
2017-11-27 10:45 ` [PATCH 08/21] x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 09/21] x86/kasan/64: Teach KASAN about the cpu_entry_area Ingo Molnar
2017-11-27 10:45 ` [PATCH 10/21] x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss Ingo Molnar
2017-11-27 10:45 ` [PATCH 11/21] x86/dumpstack: Handle stack overflow on all stacks Ingo Molnar
2017-11-27 19:26   ` Linus Torvalds
2017-11-28  4:29     ` Josh Poimboeuf
2017-11-28  5:29       ` Andy Lutomirski
2017-11-28 18:15         ` Josh Poimboeuf
2017-11-27 10:45 ` [PATCH 12/21] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct Ingo Molnar
2017-11-27 10:45 ` [PATCH 13/21] x86/entry: Remap the TSS into the CPU entry area Ingo Molnar
2017-11-27 10:45 ` [PATCH 14/21] x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 Ingo Molnar
2017-11-27 10:45 ` [PATCH 15/21] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 16/21] x86/entry/64: Use a per-CPU trampoline stack for IDT entries Ingo Molnar
2017-12-01 17:06   ` Dave Hansen
2017-12-01 17:44     ` Andy Lutomirski
2017-12-01 21:21       ` Dave Hansen
2017-12-01 21:59         ` Andy Lutomirski
2017-12-02  6:41         ` Kevin Easton
2017-11-27 10:45 ` [PATCH 17/21] x86/entry/64: Return to userspace from the trampoline stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 18/21] x86/entry/64: Create a per-CPU SYSCALL entry trampoline Ingo Molnar
2017-11-27 10:45 ` [PATCH 19/21] x86/entry/64: Move the IST stacks into 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 20/21] x86/entry/64: Remove the SYSENTER stack canary Ingo Molnar
2017-11-27 10:45 ` [PATCH 21/21] x86/entry: Clean up the SYSENTER_stack code Ingo Molnar
2017-12-01 17:59   ` Borislav Petkov

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