Fix a potential null deref when rebuilding md cache

Issue discovered using clang's static analyzer

diff --git a/changes/mdesc_null_deref b/changes/mdesc_null_deref
new file mode 100644 (file)
index 0000000..30f0280
--- /dev/null
+++ b/changes/mdesc_null_deref
@@ -0,0 +1,5 @@
+  o Minor bugfixes:
+    - Avoid a possible null-pointer dereference when rebuilding the mdesc
+      cache without actually having any descriptors to cache. Bugfix on
+      0.2.2.6-alpha. Issue discovered using clang's static analyzer.
+

diff --git a/src/or/microdesc.c b/src/or/microdesc.c
index 73d22850096472ea6a043cb24137df6aa3073b58..5740c40d5f959e583d4100b94eecb89f34732d07 100644 (file)
--- a/src/or/microdesc.c
+++ b/src/or/microdesc.c
@@ -423,7 +423,7 @@ microdesc_cache_rebuild(microdesc_cache_t *cache, int force)
   cache->journal_len = 0;
   cache->bytes_dropped = 0;
 
-  new_size = (int)cache->cache_content->size;
+  new_size = cache->cache_content ? (int)cache->cache_content->size : 0;
   log_info(LD_DIR, "Done rebuilding microdesc cache. "
            "Saved %d bytes; %d still used.",
            orig_size-new_size, new_size);