[lxc-devel] [PATCH v2 3/4] fix leak in list_active_containers()

[Serge Hallyn]

Quoting Dwight Engen (dwight.engen at oracle.com):
> Found by running the lxc-test-list test with valgrind. The names were
> put into a local array, and never freed in the success case where the
> caller didn't want the names returned and in the early out failure case.
> 
> Note we don't need to check the return from remove_from_array() because
> we just successfully added the name above.
> 
> Signed-off-by: Dwight Engen <dwight.engen at oracle.com>

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

> ---
>  src/lxc/lxccontainer.c | 72 ++++++++++++++++++++++++--------------------------
>  1 file changed, 35 insertions(+), 37 deletions(-)
> 
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index d7d3273..d57b23c 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -19,6 +19,7 @@
>   */
>  
>  #define _GNU_SOURCE
> +#include <assert.h>
>  #include <stdarg.h>
>  #include <pthread.h>
>  #include <unistd.h>
> @@ -3096,12 +3097,13 @@ free_bad:
>  	return -1;
>  }
>  
> -int list_active_containers(const char *lxcpath, char ***names, struct lxc_container ***cret)
> +int list_active_containers(const char *lxcpath, char ***nret,
> +			   struct lxc_container ***cret)
>  {
> -	int i, cfound = 0, nfound = 0;
> +	int i, ret = -1, cret_cnt = 0, ct_name_cnt = 0;
>  	int lxcpath_len;
>  	char *line = NULL;
> -	char **unique_names = NULL;
> +	char **ct_name = NULL;
>  	size_t len = 0;
>  	struct lxc_container *c;
>  
> @@ -3111,8 +3113,8 @@ int list_active_containers(const char *lxcpath, char ***names, struct lxc_contai
>  
>  	if (cret)
>  		*cret = NULL;
> -	if (names)
> -		*names = NULL;
> +	if (nret)
> +		*nret = NULL;
>  
>  	process_lock();
>  	FILE *f = fopen("/proc/net/unix", "r");
> @@ -3140,27 +3142,22 @@ int list_active_containers(const char *lxcpath, char ***names, struct lxc_contai
>  			continue;
>  		*p2 = '\0';
>  
> -		if (array_contains(&unique_names, p, nfound))
> +		if (array_contains(&ct_name, p, ct_name_cnt))
>  			continue;
>  
> -		if (!add_to_array(&unique_names, p, nfound))
> -			goto free_bad;
> +		if (!add_to_array(&ct_name, p, ct_name_cnt))
> +			goto free_cret_list;
>  
> -		cfound++;
> +		ct_name_cnt++;
>  
> -		if (!cret) {
> -			nfound++;
> +		if (!cret)
>  			continue;
> -		}
>  
>  		c = lxc_container_new(p, lxcpath);
>  		if (!c) {
>  			INFO("Container %s:%s is running but could not be loaded",
>  				lxcpath, p);
> -			if (names) {
> -				if(!remove_from_array(&unique_names, p, cfound--))
> -					goto free_bad;
> -			}
> +			remove_from_array(&ct_name, p, ct_name_cnt--);
>  			continue;
>  		}
>  
> @@ -3170,42 +3167,43 @@ int list_active_containers(const char *lxcpath, char ***names, struct lxc_contai
>  		 * fact that the command socket exists.
>  		 */
>  
> -		if (!add_to_clist(cret, c, nfound, true)) {
> +		if (!add_to_clist(cret, c, cret_cnt, true)) {
>  			lxc_container_put(c);
> -			goto free_bad;
> +			goto free_cret_list;
>  		}
> -		nfound++;
> +		cret_cnt++;
>  	}
>  
> -	if (names)
> -		*names = unique_names;
> -
> -	if (line)
> -		free(line);
> -
> -	process_lock();
> -	fclose(f);
> -	process_unlock();
> -	return nfound;
> +	assert(!nret || !cret || cret_cnt == ct_name_cnt);
> +	ret = ct_name_cnt;
> +	if (nret)
> +		*nret = ct_name;
> +	else
> +		goto free_ct_name;
> +	goto out;
>  
> -free_bad:
> -	if (names && *names) {
> -		for (i=0; i<cfound; i++)
> -			free((*names)[i]);
> -		free(*names);
> -	}
> +free_cret_list:
>  	if (cret && *cret) {
> -		for (i=0; i<nfound; i++)
> +		for (i = 0; i < cret_cnt; i++)
>  			lxc_container_put((*cret)[i]);
>  		free(*cret);
>  	}
> +
> +free_ct_name:
> +	if (ct_name) {
> +		for (i = 0; i < ct_name_cnt; i++)
> +			free(ct_name[i]);
> +		free(ct_name);
> +	}
> +
> +out:
>  	if (line)
>  		free(line);
>  
>  	process_lock();
>  	fclose(f);
>  	process_unlock();
> -	return -1;
> +	return ret;
>  }
>  
>  int list_all_containers(const char *lxcpath, char ***nret,
> -- 
> 1.8.3.1
> 
> 
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