On Thu, Sep 27, 2018 at 02:38 PM +0200, John Ferlan <jferlan@xxxxxxxxxx> wrote:
> $subj:
>
> util: Fix cgroup processing NULL pointer dereferencing
I’m fine with this change :)
>
>
> On 9/26/18 11:53 AM, Marc Hartmayer wrote:
>> When virCgroupEnableMissingControllers fails it's possible that *group
>> is still set to NULL. Therefore let's add a guard and an attribute for
>> this.
>
> Prefix paragraph with rather than at the bottom "Fixes:".
Okay.
>
> Introduced by commit 1602aa28f,
>
>>
>> [#0] virCgroupRemove(group=0x0)
>> [#1] virCgroupNewMachineSystemd
>> [#2] virCgroupNewMachine
>> [#3] qemuInitCgroup
>> [#4] qemuSetupCgroup
>> [#5] qemuProcessLaunch
>> [#6] qemuProcessStart
>> [#7] qemuDomainObjStart
>> [#8] qemuDomainCreateWithFlags
>> [#9] qemuDomainCreate
>> ...
>>
>> Fixes: 1602aa28f820ada66f707cef3e536e8572fbda1e
>
> I think it's safe to remove the stack trace...
Okay.
>
>> Reviewed-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx>
>> Reviewed-by: Bjoern Walk <bwalk@xxxxxxxxxxxxx>
>> Signed-off-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
>> ---
>> src/util/vircgroup.c | 3 ++-
>> src/util/vircgroup.h | 3 ++-
>> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> While this patch is correct to remove the NULL deref, there "may" be a
> problem with the patch that introduced this. Rather than usurp this
> thread, I'll respond to the other one and see where it takes us.
Okay.
>
> John
>
>>
>> diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
>> index 23957c82c7fa..06e1d158febb 100644
>> --- a/src/util/vircgroup.c
>> +++ b/src/util/vircgroup.c
>> @@ -1104,7 +1104,8 @@ virCgroupNewMachineSystemd(const char *name,
>>
>> error:
>> saved = virSaveLastError();
>> - virCgroupRemove(*group);
>> + if (*group)
>> + virCgroupRemove(*group);
>> virCgroupFree(group);
>> if (saved) {
>> virSetError(saved);
>> diff --git a/src/util/vircgroup.h b/src/util/vircgroup.h
>> index 1f676f21c380..9e1ae3706b1e 100644
>> --- a/src/util/vircgroup.h
>> +++ b/src/util/vircgroup.h
>> @@ -268,7 +268,8 @@ int virCgroupGetCpusetMemoryMigrate(virCgroupPtr group, bool *migrate);
>> int virCgroupSetCpusetCpus(virCgroupPtr group, const char *cpus);
>> int virCgroupGetCpusetCpus(virCgroupPtr group, char **cpus);
>>
>> -int virCgroupRemove(virCgroupPtr group);
>> +int virCgroupRemove(virCgroupPtr group)
>> + ATTRIBUTE_NONNULL(1);
>
> FWIW: This only helps if someone tried to call virCgroupRemove(NULL); it
> doesn't help if the parameter itself is NULL. One could add a "if
> (!group) return 0" to virCgroupRemove to avoid.
Thanks for pointing this out! :) I thought it could help Coverity.
>
>>
>> int virCgroupKillRecursive(virCgroupPtr group, int signum);
>> int virCgroupKillPainfully(virCgroupPtr group);
>>
>
--
Kind regards / Beste Grüße
Marc Hartmayer
IBM Deutschland Research & Development GmbH
Vorsitzende des Aufsichtsrats: Martina Koederitz
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294
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