Re: [ndctl PATCH] libdaxctl: fix memory leaks with daxctl_memory objects

[Ira Weiny <ira.weiny@intel.com>]

On Tue, Oct 01, 2019 at 11:37:26AM -0600, 'Vishal Verma' wrote:
> The daxctl_dev_alloc_mem() helper which is used to instantiate a new
> memory object did so, but neglected to attach the memory object to the
> parent 'dev' object. As a result, every invocation of
> 'daxctl_dev_get_memory() resulted in a new, orphan memory object being
> created, which also resulted in libdaxctl leaking memory.
> 
> Fix the parent association for 'mem' objects, and in free_mem, remove
> the check for 'dev' being present - mem objects will always associated
> with a dev.
> 
> Additionally, we were neglecting to free 'mem->mem_buf' in free_mem, so
> fix this up as well.
> 
> Fixes: e8bf803e359b ("libdaxctl: add a 'daxctl_memory' object for memory based operations")
> Link: https://github.com/pmem/ndctl/issues/112
> Reported-by: Michal Biesek <michal.biesek@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

Minor NIT below.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> ---
>  daxctl/lib/libdaxctl.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
> index 8abfd64..639224c 100644
> --- a/daxctl/lib/libdaxctl.c
> +++ b/daxctl/lib/libdaxctl.c
> @@ -204,8 +204,9 @@ DAXCTL_EXPORT void daxctl_region_get_uuid(struct daxctl_region *region, uuid_t u
>  
>  static void free_mem(struct daxctl_dev *dev)
>  {
> -	if (dev && dev->mem) {
> +	if (dev->mem) {

There is a comment in daxctl_dev_disable() which says:

        /* If there is a memory object, first free that */

I'm 100% sure that dev can't be NULL there.  So that comment no longer applies.

May want to remove that comment.

Ira

>  		free(dev->mem->node_path);
> +		free(dev->mem->mem_buf);
>  		free(dev->mem);
>  		dev->mem = NULL;
>  	}
> @@ -450,6 +451,7 @@ static struct daxctl_memory *daxctl_dev_alloc_mem(struct daxctl_dev *dev)
>  		goto err_node;
>  	mem->buf_len = strlen(node_base) + 256;
>  
> +	dev->mem = mem;
>  	return mem;
>  
>  err_node:
> -- 
> 2.20.1
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