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Re: [Qemu-devel] [PATCH] fw_cfg_reboot: ensure reboot_time is nonegative
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] fw_cfg_reboot: ensure reboot_time is nonegative |
Date: |
Wed, 31 Oct 2018 16:46:00 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Laszlo Ersek <address@hidden> writes:
> On 10/24/18 09:11, Li Qiang wrote:
>> This can avoid setting a negative value to
>> etc/boot-fail-wait.
>>
>> Signed-off-by: Li Qiang <address@hidden>
>> ---
>> 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
> even use a different (better) option parsing facility thatn
> qemu_opt_get(). Adding Eric and Markus.
Whenever we qemu_opt_get() a string, then convert it to a number
ourselves, we're doing it wrong. Can you use qemu_opt_get_number()?
When you have to convert string to integer, use the qemu_strtoX() that
gives you the width and signedness you need. Or maybe one of the
parse_uint*().
> Also, I would suggest forcing negative values (that were explicitly
> specified) to some sensible positive default, such as 5 seconds or so.
>
> Thanks
> Laszlo