Re: [Qemu-devel] [PATCH uq/master] fix double free the memslot in kvm_set_phys_mem

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 31 May 2013 16:52:18 +0800
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote:

> Luiz Capitulino reported that guest refused to boot and qemu
> complained with:
> kvm_set_phys_mem: error unregistering overlapping slot: Invalid argument
> 
> It is caused by commit 235e8982ad that did double free for the memslot
> so that the second one raises the -EINVAL error
> 
> Fix it by reset memory size only if it is needed
> 
> Reported-by: Luiz Capitulino <lcapitulino@redhat.com>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>

Tested-by: Luiz Capitulino <lcapitulino@redhat.com>

Thanks Xiao for the fix, and thanks everyone for debugging this issue!

> ---
>  kvm-all.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 8e7bbf8..405480e 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -206,7 +206,8 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot)
>      if (s->migration_log) {
>          mem.flags |= KVM_MEM_LOG_DIRTY_PAGES;
>      }
> -    if (mem.flags & KVM_MEM_READONLY) {
> +
> +    if (slot->memory_size && mem.flags & KVM_MEM_READONLY) {
>          /* Set the slot size to 0 before setting the slot to the desired
>           * value. This is needed based on KVM commit 75d61fbc. */
>          mem.memory_size = 0;