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

From: Steven Rostedt <rostedt@goodmis.org>
To: Shreyas Joshi <Shreyas.Joshi@biamp.com>
Cc: "pmladek@suse.com" <pmladek@suse.com>,
	"sergey.senozhatsky@gmail.com" <sergey.senozhatsky@gmail.com>,
	"shreyasjoshi15@gmail.com" <shreyasjoshi15@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] printk: handle blank console arguments passed in.
Date: Mon, 16 Mar 2020 21:39:00 -0400	[thread overview]
Message-ID: <20200316213900.6b1eb594@oasis.local.home> (raw)
In-Reply-To: <MN2PR17MB31979437E605257461AC003DFCF60@MN2PR17MB3197.namprd17.prod.outlook.com>

On Tue, 17 Mar 2020 01:34:43 +0000
Shreyas Joshi <Shreyas.Joshi@biamp.com> wrote:

Hi Shreyas!

> 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.

Please line wrap you commit messages to at most 75 characters.

> 
> Signed-off-by: Shreyas Joshi <shreyas.joshi@biamp.com>
> ---
>  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) {
> +		console_loglevel = 0;
> +		return 1;

Hmm, I wonder if this should produce a warning :-/

-- Steve

> +	}
>  	if (_braille_console_setup(&str, &brl_options))
>  		return 1;
>  
> --
> 2.20.1