Re: [PATCH] printk: handle blank console arguments passed in.

[Petr Mladek]

On Fri 2020-05-22 16:53:06, Shreyas Joshi wrote:
> If uboot passes a blank string to console_setup then it results in a trashed memory.
> Ultimately, the kernel crashes during freeing up the memory. This fix checks if there
> is a blank parameter being passed to console_setup from uboot.
> In case it detects that the console parameter is blank then
> it doesn't setup the serial device and it gracefully exits.
> 
> Signed-off-by: Shreyas Joshi <shreyas.joshi@xxxxxxxxx>
> ---
>  V1:
>     Fixed console_loglevel to default as per the review comments
> 
>  kernel/printk/printk.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index ad4606234545..e9ad730991e0 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2165,7 +2165,10 @@ static int __init console_setup(char *str)
>  	char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
>  	char *s, *options, *brl_options = NULL;
>  	int idx;
> -
> +	if (str[0] == 0) {
> +		return 1;
> +	}
>  	if (_braille_console_setup(&str, &brl_options))
>  		return 1;

I have fixed formatting and pushed it into printk/linux.git,
branch for-5.8.

Best Regards,
Petr