Subject: Re: [PATCH net,v3] net: hams: Fix deadlock caused by unsafe-irq lock in sp_get()

From: Jakub Kicinski <[email-masked]>
Date: Fri, 19 Apr 2024 20:04:53 -0700

On Sat, 20 Apr 2024 04:14:38 +0900 Jeongjun Park wrote:
> read_lock() present in sp_get() is interrupt-vulnerable, so the function needs to be modified.

I was going to make the same comments as on the other submission 
but then I realized this doesn't even build.

Please don't spam the list with completely untested code. You can
submit patches to syzbot for testing without CCing the list
or developers.

> Reported-by: [email-masked]
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Jeongjun Park <[email-masked]>
> ---
>  drivers/net/hamradio/6pack.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
> index 6ed38a3cdd73..fee583b1e59a 100644
> --- a/drivers/net/hamradio/6pack.c
> +++ b/drivers/net/hamradio/6pack.c
> @@ -373,11 +373,11 @@ static struct sixpack *sp_get(struct tty_struct *tty)
>  {
>  	struct sixpack *sp;
>  
> -	read_lock(&disc_data_lock);
> +	read_lock_irq(&disc_data_lock);
>  	sp = tty->disc_data;
>  	if (sp)
>  		refcount_inc(&sp->refcnt);
> -	read_unlock(&disc_data_lock);
> +	read_unlock_irq(&disc_data_lock);
>  
>  	return sp;
>  }