[dm-devel] [PATCH 5/5] libmultipath fix daemon memory leak in disassemble_map

[lixiaokeng]

Hi
  I'm sorry for subject with Re. I will send it  again.

On 2020/8/18 21:11, lixiaokeng wrote:
> When one iscsi device logs in and logs out with the "multipath -r"
> executed at the same time, memory leak happens in multipathd
> process.
> 
> The reason is following. When "multipath -r" is executed, the path
> will be free in configure function. Before path_discovery executed,
> iscsi device logs out. Then path_discovery will not find any path and
> there is no path in the gvecs->pathvec. When map_discovery function
> is executed, disassemble_map function will be called. Because
> gvecs->pathvec->slot is empty and is_deamon is 1, a path will be
> allocated and is not stored in gvecs->pathvec but store in
> mpp->pg. But when the mpp is removed and freed by remove_map
> function, the path will not be free and can't be find anymore.
> 
> The procedure details given as follows,
> 1."multipath -r" is executed
> main
> 	->child
> 		->reconfigure
> 			->configure
> 				->path_discovery //after iscsi logout
> 				->map_discovery
> 					->update_multipath_table
> 						->disassemble_map
> 							->alloc_path
> 2.then "multipath -r" is executed again
> main
> main
> 	->child
> 		->reconfigure
> 			->remove_maps_and_stop_waiters
> 				->remove_maps
> 
> If checking is_deamon is deleted, there are many other things need be done like in
> https://www.redhat.com/archives/dm-devel/2020-July/msg00245.html. And this
> branch develops from 0.8.3 but upstream_queue is mainline which develops from
> 0.8.4.
> Here, we skip alloc_path if pp isn't find in pathvec and process is daemon.  In
> daemon, we should not store path with incomplete information to pathvec.  The
> pathvec stores all paths in daemon, so it is reasonable keep same with pathvec.
> 
> Reported-by: Tianxiong Li <lutianxiong at huawei.com>
> Signed-off-by: Lixiaokeng <lixiaokeng at huawei.com>
> Signed-off-by: Zhiqiang Liu <liuzhiqiang26 at huawei.com>
> ---
>  libmultipath/dmparser.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/libmultipath/dmparser.c b/libmultipath/dmparser.c
> index f02c551..0f370e9 100644
> --- a/libmultipath/dmparser.c
> +++ b/libmultipath/dmparser.c
> @@ -314,6 +314,16 @@ int disassemble_map(vector pathvec, char *params, struct multipath *mpp,
>  			}
> 
>  			if (!pp) {
> +				/* daemon should keep same with pathvec */
> +				/* pp is not find in pathvec, skip it */
> +				if (is_daemon) {
> +					FREE(word);
> +					for (k = 0; k < num_paths_args; k++) {
> +						p += get_word(p, NULL);
> +					}
> +					continue;
> +				}
> +
>  				pp_unfound = 1;
>  				pp = alloc_path();
> 
> @@ -326,8 +336,8 @@ int disassemble_map(vector pathvec, char *params, struct multipath *mpp,
>  					strncpy(pp->wwid, mpp->wwid,
>  						WWID_SIZE - 1);
>  				}
> -				/* Only call this in multipath client mode */
> -				if (!is_daemon && store_path(pathvec, pp)) {
> +
> +				if (store_path(pathvec, pp)) {
>  					free_path(pp);
>  					goto out1;
>  				}
> --
>