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

[Benjamin Marzinski]

On Wed, Sep 02, 2020 at 03:19:51PM +0800, lixiaokeng wrote:
> 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.

Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>
> 
> 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);
> 
> --