Re: [Qemu-devel] [PATCH] vl: fix possible int overflow for qemu_timedate_diff()

[Paolo Bonzini <pbonzini@redhat.com>]

On 01/02/2018 12:59, Gonglei wrote:
> From: shenghualong <shenghualong@huawei.com>
> 
> When the Windows guest users set the time to year 2099,
> the return value of qemu_timedate_diff() will overflow
> with variable clock mode as below format:
> 
>  <clock offset='variable' adjustment='-1201568405' basis='utc'>
> 
> Let's change the return value of qemu_timedate_diff() from
> int to time_t to fix the possible overflow problem.
> 
> Signed-off-by: shenghualong <shenghualong@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>

Thanks, this makes sense.  However, looking at the users, you should
also change the type of:

- the diff variable in hw/timer/m48t59.c function set_alarm;

- the offset argument of the RTC_CHANGE QAPI event (to int64)

- the sec_offset and alm_sec fields of MenelausState in hw/timer/twl92230.c

- the offset argument of qemu_get_timedate.

Thanks,

Paolo

> ---
>  include/qemu-common.h | 2 +-
>  vl.c                  | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index 05319b9..6fb80aa 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -33,7 +33,7 @@ int qemu_main(int argc, char **argv, char **envp);
>  #endif
>  
>  void qemu_get_timedate(struct tm *tm, int offset);
> -int qemu_timedate_diff(struct tm *tm);
> +time_t qemu_timedate_diff(struct tm *tm);
>  
>  #define qemu_isalnum(c)		isalnum((unsigned char)(c))
>  #define qemu_isalpha(c)		isalpha((unsigned char)(c))
> diff --git a/vl.c b/vl.c
> index e517a8d..9d225da 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -146,7 +146,7 @@ int nb_nics;
>  NICInfo nd_table[MAX_NICS];
>  int autostart;
>  static int rtc_utc = 1;
> -static int rtc_date_offset = -1; /* -1 means no change */
> +static time_t rtc_date_offset = -1; /* -1 means no change */
>  QEMUClockType rtc_clock;
>  int vga_interface_type = VGA_NONE;
>  static int full_screen = 0;
> @@ -812,7 +812,7 @@ void qemu_get_timedate(struct tm *tm, int offset)
>      }
>  }
>  
> -int qemu_timedate_diff(struct tm *tm)
> +time_t qemu_timedate_diff(struct tm *tm)
>  {
>      time_t seconds;
>  
>