[dm-devel] [PATCH] multipathd fix NULL dereference in check_path

[lixiaokeng]

When iscsi login/logout and multipath command are executed
concurrently, there is a coredump.

The reason is:
check_path
    ->update_multipath_strings
        ->sync_paths
            ->orphan_path    //pp->mpp is set to NULL
        ->update_multipath_status
            ->dm_get_status  //return DMP_NOT_FOUND
    ->condlog //pp->mpp->alias, NULL dereference

Here we don't dereference pp-> mpp if it is NULL.

Signed-off-by: Lixiaokeng<lixiaokeng at huawei.com>
---
 multipathd/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/multipathd/main.c b/multipathd/main.c
index 28cb236..5ed2267 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -2010,7 +2010,7 @@ check_path (struct vectors * vecs, struct path * pp, int ticks)
 		if (ret == DMP_NOT_FOUND) {
 			/* multipath device missing. Likely removed */
 			condlog(1, "%s: multipath device '%s' not found",
-				pp->dev, pp->mpp->alias);
+				pp->dev, pp->mpp ? pp->mpp->alias : "");
 			return 0;
 		} else
 			condlog(1, "%s: Couldn't synchronize with kernel state",