[Qemu-devel] [PATCH 1/2] hw: fw_cfg: ensure reboot_time is nonegative

[Qemu-devel] [PATCH 1/2] hw: fw_cfg: ensure reboot_time is nonegative

[Li Qiang]

This can avoid setting a negative value to
etc/boot-fail-wait.

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 3fcfa35..dff6e06 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)
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 1/2] hw: fw_cfg: ensure reboot_time is nonegative

[Gerd Hoffmann]

> -    /* 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);
>      }

Hmm, values > 0xffff are reported and values < 0 are silently ignored.
I think we should be consistent here.
I'd suggest report and exit in both cases,
i.e. use error_setg(..., &error_fatal);

cheers,
  Gerd

Re: [Qemu-devel] [PATCH 1/2] hw: fw_cfg: ensure reboot_time is nonegative

[Markus Armbruster]

Gerd Hoffmann <kraxel@redhat.com> writes:

>> -    /* 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);
>>      }
>
> Hmm, values > 0xffff are reported and values < 0 are silently ignored.
> I think we should be consistent here.
> I'd suggest report and exit in both cases,

Agreed.  If the user specifies a value outside acceptable limits,
rejecting it is simpler than "correcting" it.  "Corrections" may look
convenient, but they're not worth the additional interface complexity.

> i.e. use error_setg(..., &error_fatal);

In case you mean something like

    error_setg(&error_fatal, "reboot timeout is larger than 65535");

I'd like to point to error.h:

 * Please don't error_setg(&error_fatal, ...), use error_report() and
 * exit(), because that's more obvious.