Re: [Qemu-devel] [PATCH] fw_cfg_reboot: ensure reboot_time is nonegative

[Li Qiang <liq3ea@gmail.com>]

Hello   Laszlo and Philippe ,

Thanks for your review,



Philippe Mathieu-Daudé <philmd@redhat.com> 于2018年10月25日周四 上午6:56写道：

> Hi,
>
> On 24/10/18 13:35, Laszlo Ersek wrote:
> > On 10/24/18 09:11, Li Qiang wrote:
> >> This can avoid setting a negative value to
> >> etc/boot-fail-wait.
>
> Li Qiang, can you add a qtest for this?
>
>
I will try to write one.
Is it ok to write it without this patch, as the test will be not passed?

Thanks,
Li Qiang




> >>
> >> Signed-off-by: Li Qiang <liq3ea@gmail.com>
> >> ---
> >>   hw/nvram/fw_cfg.c | 15 ++++++++++-----
> >>   1 file changed, 10 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> >> index f4a52d8..276dcb1 100644
> >> --- a/hw/nvram/fw_cfg.c
> >> +++ b/hw/nvram/fw_cfg.c
> >> @@ -199,12 +199,17 @@ static void fw_cfg_reboot(FWCfgState *s)
> >>               reboot_timeout = strtol(p, &p, 10);
> >>           }
> >>       }
> >> -    /* validate the input */
> >> -    if (reboot_timeout > 0xffff) {
> >> -        error_report("reboot timeout is larger than 65535, force it to
> 65535.");
> >> -        reboot_timeout = 0xffff;
> >> +
> >> +    if (reboot_timeout >= 0) {
> >> +        /* validate the input */
> >> +        if (reboot_timeout > 0xffff) {
> >> +            error_report("reboot timeout is larger than 65535,"
> >> +                         "force it to 65535.");
> >> +            reboot_timeout = 0xffff;
> >> +        }
> >> +        fw_cfg_add_file(s, "etc/boot-fail-wait",
> >> +                        g_memdup(&reboot_timeout, 4), 4);
> >>       }
> >> -    fw_cfg_add_file(s, "etc/boot-fail-wait", g_memdup(&reboot_timeout,
> 4), 4);
> >>   }
> >>
> >>   static void fw_cfg_write(FWCfgState *s, uint8_t value)
> >>
> >
> > I don't feel strongly about fixing this issue.
> >
> > However, if we decide to fix it, we should start with the bare-bones
> > strtol() call, visible at the top of the context. I'm not up-to-date on
> > what's the best QEMU helper function for this, but I seem to remember it
> > checks for trailing garbage, and perhaps even for range. Maybe we should
>
> Are you suggesting qemu_strtoul()? I agree this would be cleaner.
>
>

I reference the 'boot_splash_time' in fw_cfg_bootsplash.
We can also change there.



> > even use a different (better) option parsing facility thatn
> > qemu_opt_get(). Adding Eric and Markus.
> >
> > Also, I would suggest forcing negative values (that were explicitly
> > specified) to some sensible positive default, such as 5 seconds or so.
> >
> > Thanks
> > Laszlo
> >
>