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

[Li Qiang <liq3ea@gmail.com>]

Philippe Mathieu-Daudé <philmd@redhat.com> 于2018年10月30日周二 上午7:50写道：

> On 25/10/18 3:45, Li Qiang wrote:
> > Hello Laszlo and Philippe ,
> >
> > Thanks for your review,
> >
> >
> >
> > Philippe Mathieu-Daudé <philmd@redhat.com <mailto: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?
>
> It is OK to add the test after the fix, else the test would fail.
> But now your test protect from future regressions.
>
>
Ok, I think this fix is not that bad, this is the same as
'boot_splash_time'.
 As for Laszlo's consideration,  we think we can send another patch to
drop strtol in both 'boot_splash_time' and this 'reboot-timeout'.

Thanks,
Li Qiang


>
> > Thanks,
> > Li Qiang
> >
> >
> >      >>
> >      >> Signed-off-by: Li Qiang <liq3ea@gmail.com <mailto:
> 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
> >      >
> >
>