[GIT PULL] tracing: Fix misuse of strncpy to copy boot params

[GIT PULL] tracing: Fix misuse of strncpy to copy boot params

[Frederic Weisbecker]

Ingo,

Please pull this fixlet for .32 that can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/fixes

Frederic Weisbecker (1):
      tracing: Fix misuse of strncpy to copy boot params

 kernel/trace/ftrace.c |    4 ++--
 kernel/trace/trace.c  |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)
---
>From f44bec1286f516d921210a1bf843725f5d4b86ef Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Wed, 14 Oct 2009 21:17:00 +0200
Subject: [PATCH] tracing: Fix misuse of strncpy to copy boot params

While copying ftrace string boot parameters into buffers, we
use strncpy by passing the whole buffer size instead of the max
strlen the buffers can host (which is buffer size - 1), this might
lead to non-null terminated strings.

Fix that by simply using strlcpy instead.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/trace/ftrace.c |    4 ++--
 kernel/trace/trace.c  |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 37ba67e..0f4803f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2300,14 +2300,14 @@ static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;
 
 static int __init set_ftrace_notrace(char *str)
 {
-	strncpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
+	strlcpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_notrace=", set_ftrace_notrace);
 
 static int __init set_ftrace_filter(char *str)
 {
-	strncpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
+	strlcpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_filter=", set_ftrace_filter);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4506826..621d81e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -131,7 +131,7 @@ static char *default_bootup_tracer;
 
 static int __init set_ftrace(char *str)
 {
-	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
+	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
 	default_bootup_tracer = bootup_tracer_buf;
 	/* We are using ftrace early, expand it */
 	ring_buffer_expanded = 1;
-- 
1.6.2.3

Re: [GIT PULL] tracing: Fix misuse of strncpy to copy boot params

[Li Zefan]

> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 4506826..621d81e 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -131,7 +131,7 @@ static char *default_bootup_tracer;
>  
>  static int __init set_ftrace(char *str)
>  {
> -	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
> +	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);

Actually using strncpy() here is fine.

See how the str buf is used:

int register_tracer(struct tracer *type)
{
	...
	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
	...
}

>  	default_bootup_tracer = bootup_tracer_buf;
>  	/* We are using ftrace early, expand it */
>  	ring_buffer_expanded = 1;

Re: [GIT PULL] tracing: Fix misuse of strncpy to copy boot params

[Frederic Weisbecker]

On Thu, Oct 15, 2009 at 10:01:13AM +0800, Li Zefan wrote:
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 4506826..621d81e 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -131,7 +131,7 @@ static char *default_bootup_tracer;
> >  
> >  static int __init set_ftrace(char *str)
> >  {
> > -	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
> > +	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
> 
> Actually using strncpy() here is fine.
> 
> See how the str buf is used:
> 
> int register_tracer(struct tracer *type)
> {
> 	...
> 	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
> 	...
> }



Yeah. I can remove the change for this buffer and send
another pull request.

Thanks.

 
> >  	default_bootup_tracer = bootup_tracer_buf;
> >  	/* We are using ftrace early, expand it */
> >  	ring_buffer_expanded = 1;