Re: [PATCH] init - fix building bug and potential buffer overflow

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 14 May 2008 19:44:02 +0400 Cyrill Gorcunov <gorcunov@gmail.com> wrote:

> This patch does fix build bug on m68k wich does not have strncat in straight way.
> 
> What is more important - my previous patch
> 
> commit e662e1cfd434aa234b72fbc781f1d70211cb785b
> Author: Cyrill Gorcunov <gorcunov@gmail.com>
> Date:   Mon May 12 14:02:22 2008 -0700
> 
>     init: don't lose initcall return values
> 
> has introduced potential buffer overflow by wrong calculation
> of string accumulator size.
> 
> Many thanks Andreas Schwab and Geert Uytterhoeven for helping
> to catch and fix the bug.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
> 
> Index: linux-2.6.git/init/main.c
> ===================================================================
> --- linux-2.6.git.orig/init/main.c	2008-05-14 17:55:10.000000000 +0400
> +++ linux-2.6.git/init/main.c	2008-05-14 19:11:18.000000000 +0400
> @@ -702,7 +702,7 @@ static void __init do_initcalls(void)
>  
>  	for (call = __initcall_start; call < __initcall_end; call++) {
>  		ktime_t t0, t1, delta;
> -		char msgbuf[40];
> +		char msgbuf[64];
>  		int result;
>  
>  		if (initcall_debug) {
> @@ -729,11 +729,11 @@ static void __init do_initcalls(void)
>  			sprintf(msgbuf, "error code %d ", result);
>  
>  		if (preempt_count() != count) {
> -			strncat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
> +			strcat(msgbuf, "preemption imbalance ");
>  			preempt_count() = count;
>  		}
>  		if (irqs_disabled()) {
> -			strncat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
> +			strcat(msgbuf, "disabled interrupts ");
>  			local_irq_enable();
>  		}
>  		if (msgbuf[0]) {

umm, why can't m68k call strncat() from init/main.c??