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Re: [Libguestfs] [libhivex] Memory leak in hivex_node_delete_child?


On Monday 10 November 2014 18:28:52 Mahmoud Al-Qudsi wrote:
> I’m not able to pin it myself from a brief look, but it seems that
> under certain conditions a call to hivex_node_delete_child can cause
> the allocations from _hivex_get_children to not be freed properly?
> I know that if the return value of _hivex_get_children is -1, no free
> is called; but from what I can see, -1 means there is nothing to be
> freed/it’s been taken care of.
> I’ve attached the valgrind log together with the output of
> HIVEX_OPEN_DEBUG, please let me know if there’s anything else I can
> provide to make this easier.

It seems like rather hivex_node_delete_child leaks the "blocks" array 
returned by _hivex_get_children every time. The patch should be easy, 
would you be able to give it a try to check whether it fixes the leak in 
your application?

Pino Toscano
>From 854a8e763a83870e8248e132ec3a9a063f334035 Mon Sep 17 00:00:00 2001
From: Pino Toscano <ptoscano redhat com>
Date: Tue, 11 Nov 2014 11:36:30 +0100
Subject: [PATCH] lib: write: fix memory leak

Free the "blocks" array got from _hivex_get_children.

Thanks: Mahmoud Al-Qudsi
 lib/write.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/write.c b/lib/write.c
index abd12c5..33b64e4 100644
--- a/lib/write.c
+++ b/lib/write.c
@@ -902,10 +902,13 @@ hivex_node_delete_child (hive_h *h, hive_node_h node)
+  free (blocks);
   SET_ERRNO (ENOTSUP, "could not find parent to child link");
   return -1;
+  free (blocks);
   struct ntreg_nk_record *nk =
     (struct ntreg_nk_record *) ((char *) h->addr + parent);
   size_t nr_subkeys_in_nk = le32toh (nk->nr_subkeys);

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