[PATCH next] kernel/trace/trace_printk: Use kstrdup() instead of kmalloc() and strcpy()

[PATCH next] kernel/trace/trace_printk: Use kstrdup() instead of kmalloc() and strcpy()

[david.laight.linux]

From: David Laight <david.laight.linux@gmail.com>

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
This is one of a group of patches that remove potentially unbounded
strcpy() calls.

They are mostly replaced by strscpy() or, when strlen() has just been
called, with memcpy() (usually including the '\0').

Calls with copy string literals into arrays are left unchanged.
They are safe and easily detected as such.

The changes were made by getting the compiler to detect the calls and
then fixing the code by hand.

Note that all the changes are only compile tested.

Some Makefiles were changed to allow files to contain strcpy().
As well as 'difficult to fix' files, this included 'show' functions
as they really need to use sysfs_emit() or seq_printf().

All the patches are being sent individually to avoid very long cc lists.
Apologies for the terse commit messages and likely unexpected tags.
(There are about 100 patches in total.)

 kernel/trace/trace_printk.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index 3ea17af60169..98171a2398e4 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -71,10 +71,9 @@ void hold_module_trace_bprintk_format(const char **start, const char **end)
 		fmt = NULL;
 		tb_fmt = kmalloc_obj(*tb_fmt);
 		if (tb_fmt) {
-			fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
+			fmt = kstrdup(*iter, GFP_KERNEL);
 			if (fmt) {
 				list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
-				strcpy(fmt, *iter);
 				tb_fmt->fmt = fmt;
 			} else
 				kfree(tb_fmt);
-- 
2.39.5

Re: [PATCH next] kernel/trace/trace_printk: Use kstrdup() instead of kmalloc() and strcpy()

[Masami Hiramatsu]

On Sat,  6 Jun 2026 21:26:28 +0100
david.laight.linux@gmail.com wrote:

> From: David Laight <david.laight.linux@gmail.com>
> 
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
> This is one of a group of patches that remove potentially unbounded
> strcpy() calls.
> 
> They are mostly replaced by strscpy() or, when strlen() has just been
> called, with memcpy() (usually including the '\0').
> 
> Calls with copy string literals into arrays are left unchanged.
> They are safe and easily detected as such.
> 
> The changes were made by getting the compiler to detect the calls and
> then fixing the code by hand.
> 
> Note that all the changes are only compile tested.
> 
> Some Makefiles were changed to allow files to contain strcpy().
> As well as 'difficult to fix' files, this included 'show' functions
> as they really need to use sysfs_emit() or seq_printf().
> 
> All the patches are being sent individually to avoid very long cc lists.
> Apologies for the terse commit messages and likely unexpected tags.
> (There are about 100 patches in total.)
> 

This looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks,

>  kernel/trace/trace_printk.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
> index 3ea17af60169..98171a2398e4 100644
> --- a/kernel/trace/trace_printk.c
> +++ b/kernel/trace/trace_printk.c
> @@ -71,10 +71,9 @@ void hold_module_trace_bprintk_format(const char **start, const char **end)
>  		fmt = NULL;
>  		tb_fmt = kmalloc_obj(*tb_fmt);
>  		if (tb_fmt) {
> -			fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
> +			fmt = kstrdup(*iter, GFP_KERNEL);
>  			if (fmt) {
>  				list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
> -				strcpy(fmt, *iter);
>  				tb_fmt->fmt = fmt;
>  			} else
>  				kfree(tb_fmt);
> -- 
> 2.39.5
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>