Re: [libvirt] [PATCH libvirt] libxl: avoid freeing an uninitialised bitmap

Re: [libvirt] [PATCH libvirt] libxl: avoid freeing an uninitialised bitmap

[Eric Blake]

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On 06/19/2015 10:33 AM, Ian Campbell wrote:
> If vm->def->cputune.nvcpupin is 0 in libxlDomainSetVcpuAffinities (as
> seems to be the case on arm) then the VIR_FREE after cleanup: would be
> operating on an uninitialised pointer in map.map.
> 
> Fix this by using libxl_bitmap_init and libxl_bitmap_dispose in the
> appropriate places (like VIR_FREE libxl_bitmap_dispose is also

s/VIR_FREE/VIR_FREE,/

> idempotent, so there is no double free on exit from the loop).
> 
> libxl_bitmap_dispose is slightly preferable since it also sets
> map.size back to 0, avoiding a potential source of confusion.
> 
> This fixes the crashes we've been seeing in the Xen automated tests on
> ARM.
> 
> I had a glance at the handful of other users of libxl_bitmap and none
> of them looked to have a similar issue.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  src/libxl/libxl_domain.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

ACK.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [libvirt] [PATCH libvirt] libxl: avoid freeing an uninitialised bitmap

[Jim Fehlig]

On 06/19/2015 10:54 AM, Eric Blake wrote:
> On 06/19/2015 10:33 AM, Ian Campbell wrote:
>> If vm->def->cputune.nvcpupin is 0 in libxlDomainSetVcpuAffinities (as
>> seems to be the case on arm) then the VIR_FREE after cleanup: would be
>> operating on an uninitialised pointer in map.map.
>>
>> Fix this by using libxl_bitmap_init and libxl_bitmap_dispose in the
>> appropriate places (like VIR_FREE libxl_bitmap_dispose is also
> s/VIR_FREE/VIR_FREE,/
>
>> idempotent, so there is no double free on exit from the loop).
>>
>> libxl_bitmap_dispose is slightly preferable since it also sets
>> map.size back to 0, avoiding a potential source of confusion.
>>
>> This fixes the crashes we've been seeing in the Xen automated tests on
>> ARM.
>>
>> I had a glance at the handful of other users of libxl_bitmap and none
>> of them looked to have a similar issue.
>>
>> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>> ---
>>   src/libxl/libxl_domain.c |    6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
> ACK.

Modified the commit message as suggested and pushed.  Thanks!

Regards,
Jim