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Re: [Qemu-devel] [PATCH] fw_cfg_reboot: ensure reboot_time is nonegative
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH] fw_cfg_reboot: ensure reboot_time is nonegative |
Date: |
Wed, 24 Oct 2018 13:35:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
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.
Also, I would suggest forcing negative values (that were explicitly
specified) to some sensible positive default, such as 5 seconds or so.
Thanks
Laszlo