Re: [Qemu-devel] [PATCH] hmp: avoid redundant null termination of buffer

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 17 Dec 2015 18:10:59 +0530 (IST)
P J P <ppandit@redhat.com> wrote:

>    Hello,
> 
> An OOB write issue was reported by Mr Ling Liu, CC'd here. It occurs while 
> processing the 'sendkey' command, if the command argument was longer than
> the 'keyname_buf[16]' buffer.

Markus, are you planning a pull request soon?

Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>

> 
> ===
> From b0363f4c0e91671064dd7ffece8a6923c8dcaf20 Mon Sep 17 00:00:00 2001
> From: Prasad J Pandit <pjp@fedoraproject.org>
> Date: Thu, 17 Dec 2015 17:47:15 +0530
> Subject: [PATCH] hmp: avoid redundant null termination of buffer
> 
> When processing 'sendkey' command, hmp_sendkey routine null
> terminates the 'keyname_buf' array. This results in an OOB write
> issue, if 'keyname_len' was to fall outside of 'keyname_buf' array.
> Removed the redundant null termination, as pstrcpy routine already
> null terminates the target buffer.
> 
> Reported-by: Ling Liu <liuling-it@360.cn>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>   hmp.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/hmp.c b/hmp.c
> index 2140605..e530c9c 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -1746,9 +1746,7 @@ void hmp_sendkey(Monitor *mon, const QDict *qdict)
>           /* Be compatible with old interface, convert user inputted "<" */
>           if (!strncmp(keyname_buf, "<", 1) && keyname_len == 1) {
>               pstrcpy(keyname_buf, sizeof(keyname_buf), "less");
> -            keyname_len = 4;
>           }
> -        keyname_buf[keyname_len] = 0;
> 
>           keylist = g_malloc0(sizeof(*keylist));
>           keylist->value = g_malloc0(sizeof(*keylist->value));