2016-04-18 08:21:51

by Wang Xiaoqiang

Subject: [PATCH] tracing: Don't use the address of the buffer array name in copy_from_user

Hi, all,

>From 7dbacb179a4d5f9ac9d7e1b3733664b3b0fe23ae Mon Sep 17 00:00:00 2001
From: Wang Xiaoqiang <[email protected]>
Date: Mon, 18 Apr 2016 14:58:15 +0800
Subject: [PATCH] tracing: Don't use the address of the buffer array name in
copy_from_user

Fix the problem as follows:

...
char buf[64];
...
if (copy_from_user(&buf, ubuf, cnt))
...

Even though the value of "&buf" equals "buf", but there is no need
to get the address of the "buf" again. Use "buf" replace "&buf".

Signed-off-by: Wang Xiaoqiang <[email protected]>
---
kernel/trace/trace.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a2f0b9f..422ab57 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3658,7 +3658,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
if (cnt >= sizeof(buf))
return -EINVAL;

- if (copy_from_user(&buf, ubuf, cnt))
+ if (copy_from_user(buf, ubuf, cnt))
return -EFAULT;

buf[cnt] = 0;
@@ -4474,7 +4474,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
if (cnt > MAX_TRACER_SIZE)
cnt = MAX_TRACER_SIZE;

- if (copy_from_user(&buf, ubuf, cnt))
+ if (copy_from_user(buf, ubuf, cnt))
return -EFAULT;

buf[cnt] = 0;
@@ -5264,7 +5264,7 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
if (cnt >= sizeof(buf))
return -EINVAL;

- if (copy_from_user(&buf, ubuf, cnt))
+ if (copy_from_user(buf, ubuf, cnt))
return -EFAULT;

buf[cnt] = 0;
--
2.1.4

2016-04-26 16:37:18

by Steven Rostedt

Subject: Re: [PATCH] tracing: Don't use the address of the buffer array name in copy_from_user

On Mon, 18 Apr 2016 15:23:29 +0800
Wang Xiaoqiang <[email protected]> wrote:

> Hi, all,
>
> From 7dbacb179a4d5f9ac9d7e1b3733664b3b0fe23ae Mon Sep 17 00:00:00 2001
> From: Wang Xiaoqiang <[email protected]>
> Date: Mon, 18 Apr 2016 14:58:15 +0800
> Subject: [PATCH] tracing: Don't use the address of the buffer array name in
> copy_from_user
>
> Fix the problem as follows:

What problem is being fixed?

>
> ...
> char buf[64];
> ...
> if (copy_from_user(&buf, ubuf, cnt))
> ...
>
> Even though the value of "&buf" equals "buf", but there is no need
> to get the address of the "buf" again. Use "buf" replace "&buf".

I'll take this, but more as a cleanup and not a "fix".

Thanks,

-- Steve

>
> Signed-off-by: Wang Xiaoqiang <[email protected]>
> ---
> kernel/trace/trace.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index a2f0b9f..422ab57 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3658,7 +3658,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
> if (cnt >= sizeof(buf))
> return -EINVAL;
>
> - if (copy_from_user(&buf, ubuf, cnt))
> + if (copy_from_user(buf, ubuf, cnt))
> return -EFAULT;
>
> buf[cnt] = 0;
> @@ -4474,7 +4474,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
> if (cnt > MAX_TRACER_SIZE)
> cnt = MAX_TRACER_SIZE;
>
> - if (copy_from_user(&buf, ubuf, cnt))
> + if (copy_from_user(buf, ubuf, cnt))
> return -EFAULT;
>
> buf[cnt] = 0;
> @@ -5264,7 +5264,7 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
> if (cnt >= sizeof(buf))
> return -EINVAL;
>
> - if (copy_from_user(&buf, ubuf, cnt))
> + if (copy_from_user(buf, ubuf, cnt))
> return -EFAULT;
>
> buf[cnt] = 0;