[dm-devel] [PATCH] multipathd: fix mpp->hwe handling on path removal

[Martin Wilck]

Christophe,

without this patch, current upstream multipath _crashes_ on path
removal. Please apply it. If reviewers disagree with this fix, I can
post updates later.

Martin

On Mon, 2018-06-25 at 17:10 +0200, Martin Wilck wrote:
> In my previous patch f0462f0c8338, I overlooked that during path
> removal,
> the path that mpp->hwe references may be removed and and thus mpp-
> >hwe
> may become stale. Fix it.
> 
> Fixes: f0462f0c8338 "libmultipath: use vector for for pp->hwe and mp-
> >hwe"
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  multipathd/main.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 72f06b56..cc493c18 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -1076,6 +1076,14 @@ ev_remove_path (struct path *pp, struct
> vectors * vecs, int need_do_map)
>  				mpp->alias);
>  			goto fail;
>  		}
> +
> +		/*
> +		 * Make sure mpp->hwe doesn't point to freed memory
> +		 * We call extract_hwe_from_path() below to restore
> mpp->hwe
> +		 */
> +		if (mpp->hwe == pp->hwe)
> +			mpp->hwe = NULL;
> +
>  		if ((i = find_slot(mpp->paths, (void *)pp)) != -1)
>  			vector_del_slot(mpp->paths, i);
>  
> @@ -1109,6 +1117,9 @@ ev_remove_path (struct path *pp, struct vectors
> * vecs, int need_do_map)
>  			 */
>  		}
>  
> +		if (mpp->hwe == NULL)
> +			extract_hwe_from_path(mpp);
> +
>  		if (setup_map(mpp, params, PARAMS_SIZE, vecs)) {
>  			condlog(0, "%s: failed to setup map for"
>  				" removal of path %s", mpp->alias,
> pp->dev);

-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)