[dm-devel] [PATCH 07/14] libmultipath: check return value of dm_mapname in, sysfs_check_holders

[lixiaokeng]

In sysfs_check_holders func, table_name is obtained by calling
dm_mapname func, and then call dm_reassign_table for reassigning
table. However, we donnot check whether dm_mapname func returns
NULL, and then it may cause a segmentation fault in dm_task_set_name.

Here, we will check whether dm_mapname func returns NULL before
using it.

Signed-off-by: Zhiqiang Liu <liuzhiqiang26 at huawei.com>
Signed-off-by: Lixiaokeng <lixiaokeng at huawei.com>
---
 libmultipath/sysfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
index 12a82d95..5390de62 100644
--- a/libmultipath/sysfs.c
+++ b/libmultipath/sysfs.c
@@ -278,7 +278,11 @@ int sysfs_check_holders(char * check_devt, char * new_devt)
 			continue;
 		}
 		table_name = dm_mapname(major, table_minor);
-
+		if (!table_name) {
+			condlog(2, "%s: mapname not found for %d:%d", check_dev,
+				major, table_minor);
+			continue;
+		}
 		condlog(0, "%s: reassign table %s old %s new %s", check_dev,
 			table_name, check_devt, new_devt);

--