Re: [PATCH] tty: vt: keyboard: Free dynamic-memory only if kmalloc'ed.

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Nov 06, 2021 at 03:02:02PM +0530, Ajay Garg wrote:
> In "vt_do_kdgkb_ioctl", kbs is kmalloced, if cmd is one of
> KDGKBSENT or KDGSKBSENT.
> 
> If cmd is none of the above, no kbs is kmalloced, and thus,
> kbs must only be kfreed if it is really kmalloced.
> 
> Signed-off-by: Ajay Garg <ajaygargnsit@gmail.com>
> ---
>  drivers/tty/vt/keyboard.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index dfef7de8a057..95839987c79c 100644
> --- a/drivers/tty/vt/keyboard.c
> +++ b/drivers/tty/vt/keyboard.c
> @@ -2049,7 +2049,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
>  {
>  	unsigned char kb_func;
>  	unsigned long flags;
> -	char *kbs;
> +	char *kbs = NULL;
>  	int ret;
>  
>  	if (get_user(kb_func, &user_kdgkb->kb_func))
> @@ -2092,7 +2092,8 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
>  		break;
>  	}
>  
> -	kfree(kbs);
> +        if(kbs)
> +            kfree(kbs);
>  
>  	return ret;
>  }
> -- 
> 2.30.2
> 


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