btrfs-progs: check result of first_cache_extent

If the tree's empty, we'll get NULL and dereference it.

Resolves-Coverity-CID: 1248828
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/cmds-check.c b/cmds-check.c
index 6eea36c..3e7a4eb 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -8075,6 +8075,8 @@ static void free_roots_info_cache(void)
                struct root_item_info *rii;
 
                entry = first_cache_extent(roots_info_cache);
+               if (!entry)
+                       break;
                remove_cache_extent(roots_info_cache, entry);
                rii = container_of(entry, struct root_item_info, cache_extent);
                free(rii);