lkml.org 
[lkml]   [2019]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v2 0/9] kprobes: Fix and improve blacklist symbols
On Sat, Jan 12, 2019 at 11:25:40AM +0900, Masami Hiramatsu wrote:
...
> And I found several functions which must be blacklisted.
> - optprobe template code, which is just a template code and
> never be executed. Moreover, since it can be copied and
> reused, if we probe it, it modifies the template code and
> can cause a crash. ([1/9][2/9])
> - functions which is called before kprobe_int3_handler()
> handles kprobes. This can cause a breakpoint recursion. ([3/9])
> - IRQ entry text, which should not be probed since register/pagetable
> status has not been stable at that point. ([4/9])
> - Suffixed symbols, like .constprop, .part etc. Those suffixed
> symbols never be blacklisted even if the non-suffixed version
> has been blacklisted. ([5/9])
> - hardirq tracer also works before int3 handling. ([6/9])
> - preempt_check debug function also is involved in int3 handling.
> ([7/9])
> - RCU debug routine is also called before kprobe_int3_handler().
> ([8/9])
> - Some lockdep functions are also involved in int3 handling.
> ([9/9])
>
> Of course there still may be some functions which can be called
> by configuration change, I'll continue to test it.

Hi Masami,

I think I've found another recursion problem. Could you include also
this one?

Thanks,

From: Andrea Righi <righi.andrea@gmail.com>
Subject: [PATCH] kprobes: prohibit probing on bsearch()

Since kprobe breakpoing handler is using bsearch(), probing on this
routine can cause recursive breakpoint problem.

int3
->do_int3()
->ftrace_int3_handler()
->ftrace_location()
->ftrace_location_range()
->bsearch() -> int3

Prohibit probing on bsearch().

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
---
lib/bsearch.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/lib/bsearch.c b/lib/bsearch.c
index 18b445b010c3..82512fe7b33c 100644
--- a/lib/bsearch.c
+++ b/lib/bsearch.c
@@ -11,6 +11,7 @@

#include <linux/export.h>
#include <linux/bsearch.h>
+#include <linux/kprobes.h>

/*
* bsearch - binary search an array of elements
@@ -53,3 +54,4 @@ void *bsearch(const void *key, const void *base, size_t num, size_t size,
return NULL;
}
EXPORT_SYMBOL(bsearch);
+NOKPROBE_SYMBOL(bsearch);
--
2.17.1
\
 
 \ /
  Last update: 2019-01-12 14:35    [W:0.155 / U:1.512 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site