[Mesa-dev] [PATCH] util/ralloc: set prev-pointers correctly in ralloc_adopt

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

Found by inspection.

I'm not aware of any actual failures caused by this, but a precise
sequence of ralloc_adopt and ralloc_free should be able to cause
problems.
---
 src/util/ralloc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/util/ralloc.c b/src/util/ralloc.c
index bf46439df4e..50e629fe450 100644
--- a/src/util/ralloc.c
+++ b/src/util/ralloc.c
@@ -304,24 +304,26 @@ ralloc_adopt(const void *new_ctx, void *old_ctx)
    new_info = get_header(new_ctx);
 
    /* If there are no children, bail. */
    if (unlikely(old_info->child == NULL))
       return;
 
    /* Set all the children's parent to new_ctx; get a pointer to the last child. */
    for (child = old_info->child; child->next != NULL; child = child->next) {
       child->parent = new_info;
    }
+   child->parent = new_info;
 
    /* Connect the two lists together; parent them to new_ctx; make old_ctx empty. */
    child->next = new_info->child;
-   child->parent = new_info;
+   if (new_info->child)
+      new_info->child->prev = child;
    new_info->child = old_info->child;
    old_info->child = NULL;
 }
 
 void *
 ralloc_parent(const void *ptr)
 {
    ralloc_header *info;
 
    if (unlikely(ptr == NULL))
-- 
2.11.0