[dm-devel] [PATCH v2] libmultipath: fix memory leaks in coalesce_paths

[Martin Wilck]

Hi lixiaokeng,

On Thu, 2020-10-22 at 15:28 +0800, lixiaokeng wrote:
> When multipath -F are executed first and multipath -v2 or
> -d are executed later, asan will warn memory leaks. The
> reason is that the mpp allocated in coalesce_paths isn't
> freed. Here we use newmp to store mpp. If newmp need not
> be copied to mpvec, we free newmp at the end of the func.
> 
> Signed-off-by: Lixiaokeng <lixiaokeng at huawei.com>
> Signed-off-by: Zhiqiang Liu <liuzhiqiang26 at huawei.com>
> Signed-off-by: Linfeilong <linfeilong at huawei.com>

Thanks. Please see below.

> ---
>  libmultipath/configure.c | 66 +++++++++++++++++++++++++-------------
> --
>  1 file changed, 41 insertions(+), 25 deletions(-)
> 
> diff --git a/libmultipath/configure.c b/libmultipath/configure.c
> index 6fb477fc..9d6eeba1 100644
> --- a/libmultipath/configure.c
> +++ b/libmultipath/configure.c
> @@ -1132,7 +1132,7 @@ out:
>   * FORCE_RELOAD_WEAK: existing maps are compared to the current conf
> and only
>   * reloaded in DM if there's a difference. This is useful during
> startup.
>   */
> -int coalesce_paths (struct vectors * vecs, vector newmp, char *
> refwwid,
> +int coalesce_paths (struct vectors *vecs, vector mpvec, char
> *refwwid,
>  		    int force_reload, enum mpath_cmds cmd)
>  {
>  	int ret = CP_FAIL;
> @@ -1144,10 +1144,20 @@ int coalesce_paths (struct vectors * vecs,
> vector newmp, char * refwwid,
>  	struct path * pp2;
>  	vector curmp = vecs->mpvec;
>  	vector pathvec = vecs->pathvec;
> +	vector newmp = NULL;

This initialization is not necessary.

>  	struct config *conf;
>  	int allow_queueing;
>  	struct bitfield *size_mismatch_seen;
> 
> +	if (mpvec)
> +		newmp = mpvec;
> +	else
> +		newmp = vector_alloc();
> +	if (!newmp) {
> +		condlog(0, "can not allocate newmp");
> +		return ret;
> +	}
> +
>  	/* ignore refwwid if it's empty */
>  	if (refwwid && !strlen(refwwid))
>  		refwwid = NULL;
> @@ -1270,8 +1280,14 @@ int coalesce_paths (struct vectors * vecs,
> vector newmp, char * refwwid,
>  				goto out;
>  			}
>  		}
> -		if (r == DOMAP_DRY)
> +		if (r == DOMAP_DRY) {
> +			if (!vector_alloc_slot(newmp)) {
> +				remove_map(mpp, vecs->pathvec, vecs-
> >mpvec, KEEP_VEC);
> +				goto out;
> +			}
> +			vector_set_slot(newmp, mpp);
>  			continue;
> +		}
> 
>  		if (r == DOMAP_EXIST && mpp->action == ACT_NOTHING &&
>  		    force_reload == FORCE_RELOAD_WEAK)
> @@ -1307,44 +1323,44 @@ int coalesce_paths (struct vectors * vecs,
> vector newmp, char * refwwid,
>  			print_multipath_topology(mpp, verbosity);
>  		}
> 
> -		if (newmp) {
> -			if (mpp->action != ACT_REJECT) {
> -				if (!vector_alloc_slot(newmp))
> -					goto out;
> -				vector_set_slot(newmp, mpp);
> +		if (mpp->action != ACT_REJECT) {
> +			if (!vector_alloc_slot(newmp)) {
> +				remove_map(mpp, vecs->pathvec, vecs-
> >mpvec, KEEP_VEC);
> +				goto out;
>  			}
> -			else
> -				remove_map(mpp, vecs->pathvec, vecs-
> >mpvec,
> -					   KEEP_VEC);
> +			vector_set_slot(newmp, mpp);
>  		}
> +		else
> +			remove_map(mpp, vecs->pathvec, vecs->mpvec,
> +				   KEEP_VEC);
>  	}
>  	/*
>  	 * Flush maps with only dead paths (ie not in sysfs)
>  	 * Keep maps with only failed paths
>  	 */
> -	if (newmp) {
> -		vector_foreach_slot (newmp, mpp, i) {
> -			char alias[WWID_SIZE];
> +	vector_foreach_slot (newmp, mpp, i) {
> +		char alias[WWID_SIZE];
> 
> -			if (!deadmap(mpp))
> -				continue;
> +		if (!deadmap(mpp))
> +			continue;
> 
> -			strlcpy(alias, mpp->alias, WWID_SIZE);
> +		strlcpy(alias, mpp->alias, WWID_SIZE);
> 
> -			vector_del_slot(newmp, i);
> -			i--;
> -			remove_map(mpp, vecs->pathvec, vecs->mpvec,
> KEEP_VEC);
> +		vector_del_slot(newmp, i);
> +		i--;
> +		remove_map(mpp, vecs->pathvec, vecs->mpvec, KEEP_VEC);
> 
> -			if (dm_flush_map(alias))
> -				condlog(2, "%s: remove failed (dead)",
> -					alias);
> -			else
> -				condlog(2, "%s: remove (dead)", alias);
> -		}
> +		if (dm_flush_map(alias))
> +			condlog(2, "%s: remove failed (dead)",
> +				alias);
> +		else
> +			condlog(2, "%s: remove (dead)", alias);

Previously, this code, which flushes maps that aren't valid any more,
would only be called from multipathd() -> reconfigure(), because in all
other cases newmp was NULL.

AFAICS, you will now call dm_flush_map() even if called with
newmp==NULL (this means, from cli_add_map(), or from multipath, even if
called with CMD_DRY_RUN). I don't think that's what we want.

Regards,
Martin