On 12/10/18 15:48, Max Reitz wrote:
Hi, On 31.08.18 20:16, Liam Merwick wrote:The dev_id returned by the call to blk_get_attached_dev_id() in blk_root_get_parent_desc() can be NULL (an internal call to object_get_canonical_path may have returned NULL) so it should be checked before dereferencing. Signed-off-by: Liam Merwick <liam.merw...@oracle.com> Reviewed-by: Darren Kenny <darren.ke...@oracle.com> Reviewed-by: Mark Kanda <mark.ka...@oracle.com> --- block/block-backend.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/block-backend.c b/block/block-backend.c index fa120630be83..210eee75006a 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -136,7 +136,7 @@ static char *blk_root_get_parent_desc(BdrvChild *child) }dev_id = blk_get_attached_dev_id(blk);- if (*dev_id) { + if (dev_id && *dev_id) { return dev_id;I rather think that blk_get_attached_dev_id() needs attention first. It returns an explicitly empty string if blk->dev is NULL. If NULL was a valid return value, it should just return NULL there. Besides this caller, there are two callers that pass the dev_id to qapi_event_send_device_tray_moved(). Now in practice that allows the string to be NULL, but there is a comment in visit_type_str() that says one should not pass NULL. So it's either changing blk_get_attached_dev_id() to return NULL when there is no valid ID (instead of the empty string, and then we could save ourselves the check "*dev_id" here and elsewhere), but then we have to fix all callers. Or we make it return an empty string if object_get_canonical_path() returned NULL.
I went with the latter and now (in upcoming v4) check the return value from object_get_canonical_path() and return an empty string if it's NULL.
Regards, Liam
Max} else { /* TODO Callback into the BB owner for something more detailed */
