Re: [PATCH 1/2] of: Fix crash if an earlycon driver is not found

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On Sun,  9 Nov 2014 00:55:47 -0800
, Kevin Cernekee <cernekee@xxxxxxxxx>
 wrote:
> __earlycon_of_table_sentinel.compatible is a char[128], not a pointer, so
> it will never be NULL.  Checking it against NULL causes the match loop to
> run past the end of the array, and eventually match a bogus entry, under
> the following conditions:
> 
>  - Kernel command line specifies "earlycon" with no parameters
>  - DT has a stdout-path pointing to a UART node
>  - The UART driver doesn't use OF_EARLYCON_DECLARE (or maybe the console
>    driver is compiled out)
> 
> Fix this by checking to see if match->compatible is a non-empty string.
> 
> Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 3.16+

Applied, thanks. Although a more robust fix would probably to be
checking for the end address of the section. This is a safe fix though,
so I'm picking it up.

g.

> ---
>  drivers/of/fdt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index d1ffca8..30e97bc 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -773,7 +773,7 @@ int __init early_init_dt_scan_chosen_serial(void)
>  	if (offset < 0)
>  		return -ENODEV;
>  
> -	while (match->compatible) {
> +	while (match->compatible[0]) {
>  		unsigned long addr;
>  		if (fdt_node_check_compatible(fdt, offset, match->compatible)) {
>  			match++;
> -- 
> 2.1.1
> 

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