[tor-commits] [tor/master] Clear memory in smartlist_remove_keeporder.

[dgoulet at torproject.org]

commit 670d0f9f5bb7d73ad236a035ed7bd69e96cadd41
Author: Tobias Stoeckmann <tobias at stoeckmann.org>
Date:   Sat Apr 13 16:55:36 2019 +0200

    Clear memory in smartlist_remove_keeporder.
    
    The smartlist functions take great care to reset unused pointers inside
    the smartlist memory to NULL.
    
    The function smartlist_remove_keeporder does not clear memory in such
    way when elements have been removed. Therefore call memset after the
    for-loop that removes elements. If no element is removed, it is
    effectively a no-op.
    
    Signed-off-by: Tobias Stoeckmann <tobias at stoeckmann.org>
---
 changes/ticket30176                     | 4 ++++
 src/lib/smartlist_core/smartlist_core.c | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/changes/ticket30176 b/changes/ticket30176
new file mode 100644
index 000000000..da23760ce
--- /dev/null
+++ b/changes/ticket30176
@@ -0,0 +1,4 @@
+  o Minor features (defense in depth):
+    - In smartlist_remove_keeporder(), set any pointers that become
+      unused to NULL, in case a bug causes them to be used later. Closes
+      ticket 30176.  Patch from Tobias Stoeckmann.
diff --git a/src/lib/smartlist_core/smartlist_core.c b/src/lib/smartlist_core/smartlist_core.c
index 5947e7627..6b0a305a9 100644
--- a/src/lib/smartlist_core/smartlist_core.c
+++ b/src/lib/smartlist_core/smartlist_core.c
@@ -177,6 +177,8 @@ smartlist_remove_keeporder(smartlist_t *sl, const void *element)
       sl->list[i++] = sl->list[j];
     }
   }
+  memset(sl->list + sl->num_used, 0,
+         sizeof(void *) * (num_used_orig - sl->num_used));
 }
 
 /** If <b>sl</b> is nonempty, remove and return the final element.  Otherwise,