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[OpenWrt-Devel,v2,libubox,10/10] avl: guard against theoretical null pointer dereference

Message ID 20191120214353.27652-11-ynezz@true.cz
State Accepted
Delegated to: Petr Štetiar
Headers show
Series fixes, unit tests and GitLab CI | expand

Commit Message

Petr Štetiar Nov. 20, 2019, 9:43 p.m. UTC 
clang-10 analyzer reports following:

 avl.c:671:25: warning: Access to field 'parent' results in a dereference of a null pointer (loaded from field 'right')
     node->right->parent = parent;
           ~~~~~         ^

Which seems to be impossible to trigger via exported AVL public API, but
it could be probably trigerred by fiddling with the AVL tree node struct
members manually as they are exposed.

Signed-off-by: Petr Štetiar <ynezz@true.cz>
---
 avl.c | 2 ++
 1 file changed, 2 insertions(+)
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Patch

diff --git a/avl.c b/avl.c
index 8d0bf65aaa5b..79ea5c798b64 100644
--- a/avl.c
+++ b/avl.c
@@ -45,6 +45,7 @@ 
 #include <string.h>
 
 #include "avl.h"
+#include "assert.h"
 #include "list.h"
 
 /**
@@ -668,6 +669,7 @@  avl_delete_worker(struct avl_tree *tree, struct avl_node *node)
       return;
     }
 
+    assert(node->right);
     node->right->parent = parent;
 
     if (parent->left == node)