Re: [PATCH v3 20/26] x86: Fix x86_cpu_new() error handling
On 02/07/20 06:51, Markus Armbruster wrote:
> Igor, Paolo, you showed me the error in v2. Could you have a look at
> this revision?
>
> Markus Armbruster writes:
>
>> The Error ** argument must be NULL, _abort, _fatal, or a
>> pointer to a variable containing NULL. Passing an argument of the
>> latter kind twice without clearing it in between is wrong: if the
>> first call sets an error, it no longer points to NULL for the second
>> call.
>>
>> x86_cpu_new() is wrong that way: it passes _err to
>> object_property_set_uint() without checking it, and then to
>> qdev_realize(). If both fail, we'll trip error_setv()'s assertion.
>> To assess the bug's impact, we'd need to figure out how to make both
>> calls fail. Too much work for ignorant me, sorry.
>>
>> Fix by checking for failure right away.
>>
>> Cc: Igor Mammedov
>> Cc: Paolo Bonzini
>> Cc: Richard Henderson
>> Cc: Eduardo Habkost
>> Signed-off-by: Markus Armbruster
>> ---
>> hw/i386/x86.c | 8 +---
>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
>> index 34229b45c7..93f7371a56 100644
>> --- a/hw/i386/x86.c
>> +++ b/hw/i386/x86.c
>> @@ -118,14 +118,16 @@ uint32_t x86_cpu_apic_id_from_index(X86MachineState
>> *x86ms,
>>
>> void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, Error **errp)
>> {
>> -Object *cpu = NULL;
>> Error *local_err = NULL;
>> -
>> -cpu = object_new(MACHINE(x86ms)->cpu_type);
>> +Object *cpu = object_new(MACHINE(x86ms)->cpu_type);
>>
>> object_property_set_uint(cpu, apic_id, "apic-id", _err);
>> +if (local_err) {
>> +goto out;
>> +}
>> qdev_realize(DEVICE(cpu), NULL, _err);
>>
>> +out:
>> object_unref(cpu);
>> error_propagate(errp, local_err);
>> }
>
Yes, this looks good. Thanks!
Reviewed-by: Paolo Bonzini
Paolo
Re: [PATCH v3 20/26] x86: Fix x86_cpu_new() error handling
Igor, Paolo, you showed me the error in v2. Could you have a look at
this revision?
Markus Armbruster writes:
> The Error ** argument must be NULL, _abort, _fatal, or a
> pointer to a variable containing NULL. Passing an argument of the
> latter kind twice without clearing it in between is wrong: if the
> first call sets an error, it no longer points to NULL for the second
> call.
>
> x86_cpu_new() is wrong that way: it passes _err to
> object_property_set_uint() without checking it, and then to
> qdev_realize(). If both fail, we'll trip error_setv()'s assertion.
> To assess the bug's impact, we'd need to figure out how to make both
> calls fail. Too much work for ignorant me, sorry.
>
> Fix by checking for failure right away.
>
> Cc: Igor Mammedov
> Cc: Paolo Bonzini
> Cc: Richard Henderson
> Cc: Eduardo Habkost
> Signed-off-by: Markus Armbruster
> ---
> hw/i386/x86.c | 8 +---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 34229b45c7..93f7371a56 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -118,14 +118,16 @@ uint32_t x86_cpu_apic_id_from_index(X86MachineState
> *x86ms,
>
> void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, Error **errp)
> {
> -Object *cpu = NULL;
> Error *local_err = NULL;
> -
> -cpu = object_new(MACHINE(x86ms)->cpu_type);
> +Object *cpu = object_new(MACHINE(x86ms)->cpu_type);
>
> object_property_set_uint(cpu, apic_id, "apic-id", _err);
> +if (local_err) {
> +goto out;
> +}
> qdev_realize(DEVICE(cpu), NULL, _err);
>
> +out:
> object_unref(cpu);
> error_propagate(errp, local_err);
> }
[PATCH v3 20/26] x86: Fix x86_cpu_new() error handling
The Error ** argument must be NULL, _abort, _fatal, or a
pointer to a variable containing NULL. Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.
x86_cpu_new() is wrong that way: it passes _err to
object_property_set_uint() without checking it, and then to
qdev_realize(). If both fail, we'll trip error_setv()'s assertion.
To assess the bug's impact, we'd need to figure out how to make both
calls fail. Too much work for ignorant me, sorry.
Fix by checking for failure right away.
Cc: Igor Mammedov
Cc: Paolo Bonzini
Cc: Richard Henderson
Cc: Eduardo Habkost
Signed-off-by: Markus Armbruster
---
hw/i386/x86.c | 8 +---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 34229b45c7..93f7371a56 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -118,14 +118,16 @@ uint32_t x86_cpu_apic_id_from_index(X86MachineState
*x86ms,
void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, Error **errp)
{
-Object *cpu = NULL;
Error *local_err = NULL;
-
-cpu = object_new(MACHINE(x86ms)->cpu_type);
+Object *cpu = object_new(MACHINE(x86ms)->cpu_type);
object_property_set_uint(cpu, apic_id, "apic-id", _err);
+if (local_err) {
+goto out;
+}
qdev_realize(DEVICE(cpu), NULL, _err);
+out:
object_unref(cpu);
error_propagate(errp, local_err);
}
--
2.26.2
