Commit c13324a5 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

x86/kprobes: Prohibit probing on functions before kprobe_int3_handler() 



Prohibit probing on the functions called before kprobe_int3_handler()
in do_int3(). More specifically, ftrace_int3_handler(),
poke_int3_handler(), and ist_enter(). And since rcu_nmi_enter() is
called by ist_enter(), it also should be marked as NOKPROBE_SYMBOL.

Since those are handled before kprobe_int3_handler(), probing those
functions can cause a breakpoint recursion and crash the kernel.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998793571.31052.11301258949601150994.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 877b145f

arch/x86/kernel/alternative.c

+2 −1
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/stop_machine.h>

#include <linux/slab.h>

#include <linux/kdebug.h>

#include <linux/kprobes.h>

#include <asm/text-patching.h>

#include <asm/alternative.h>

#include <asm/sections.h>
@@ -764,8 +765,8 @@ int poke_int3_handler(struct pt_regs *regs) 
	regs->ip = (unsigned long) bp_int3_handler;



	return 1;



}

NOKPROBE_SYMBOL(poke_int3_handler);



/**

 * text_poke_bp() -- update instructions on live kernel on SMP

arch/x86/kernel/ftrace.c

+2 −1
Original line number Diff line number Diff line
@@ -269,7 +269,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func) 
	return ret;

}



static int is_ftrace_caller(unsigned long ip)

static nokprobe_inline int is_ftrace_caller(unsigned long ip)

{

	if (ip == ftrace_update_func)

		return 1;
@@ -299,6 +299,7 @@ int ftrace_int3_handler(struct pt_regs *regs) 


	return 1;

}

NOKPROBE_SYMBOL(ftrace_int3_handler);



static int ftrace_write(unsigned long ip, const char *val, int size)

{

arch/x86/kernel/traps.c

+1 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ void ist_enter(struct pt_regs *regs) 
	/* This code is a bit fragile.  Test it. */

	RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");

}

NOKPROBE_SYMBOL(ist_enter);



void ist_exit(struct pt_regs *regs)

{

kernel/rcu/tree.c

+2 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ 
#include <linux/suspend.h>

#include <linux/ftrace.h>

#include <linux/tick.h>

#include <linux/kprobes.h>



#include "tree.h"

#include "rcu.h"
@@ -872,6 +873,7 @@ void rcu_nmi_enter(void) 
{

	rcu_nmi_enter_common(false);

}

NOKPROBE_SYMBOL(rcu_nmi_enter);



/**

 * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle

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