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Re: [libvirt] [PATCH 3/3] cgroup: fix libvirtd crash caused by messed memory



On Fri, Aug 31, 2012 at 05:22:59PM +0800, Guannan Ren wrote:
> The variable max_id is initialized again in the step of
> getting cpu mapping variable map2. But in the next for loop
> we still expect original value of max_id, the bug will
> crash libvirtd when using on NUMA machine with big number
> of cpus.
> ---
>  src/qemu/qemu_driver.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 5081b52..53d6e5b 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -13496,7 +13496,7 @@ qemuDomainGetPercpuStats(virDomainPtr domain,
>      char *map = NULL;
>      char *map2 = NULL;
>      int rv = -1;
> -    int i, max_id;
> +    int i, id, max_id;
>      char *pos;
>      char *buf = NULL;
>      unsigned long long *sum_cpu_time = NULL;
> @@ -13537,10 +13537,13 @@ qemuDomainGetPercpuStats(virDomainPtr domain,
>      /* return percpu cputime in index 0 */
>      param_idx = 0;
>  
> +    /* number of cpus to compute */
> +    id = max_id;
> +
>      if (max_id - start_cpu > ncpus - 1)
> -        max_id = start_cpu + ncpus - 1;
> +        id = start_cpu + ncpus - 1;
>  
> -    for (i = 0; i <= max_id; i++) {
> +    for (i = 0; i <= id; i++) {
>          if (!map[i]) {
>              cpu_time = 0;
>          } else if (virStrToLong_ull(pos, &pos, 10, &cpu_time) < 0) {
> @@ -13580,7 +13583,7 @@ qemuDomainGetPercpuStats(virDomainPtr domain,
>      }
>  
>      sum_cpu_pos = sum_cpu_time;
> -    for (i = 0; i <= max_id; i++) {
> +    for (i = 0; i <= id; i++) {
>          if (!map[i])
>              cpu_time = 0;
>          else

  ACK, that sounds right,

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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