Re: [Dnsmasq-discuss] [PATCH] Set pointers to NULL after memory is freed

2023-10-09 Thread Simon Kelley 

On 08/10/2023 09:44, renmingshuai via Dnsmasq-discuss wrote:
Set pointers to NULL after memory is freed to reduce dangling pointers, 
although they are later set to new values.


 From 5567d99099191f0cdb2922555e6ade2634f94f30 Mon Sep 17 00:00:00 2001

From: renmingshuai 

Date: Sun, 8 Oct 2023 16:06:46 +0800

Subject: [PATCH] Set pointers to NULL after memory is freed

---

src/option.c | 3 +++

1 file changed, 3 insertions(+)

diff --git a/src/option.c b/src/option.c

index 286f06b..23601e1 100644

--- a/src/option.c

+++ b/src/option.c

@@ -5732,6 +5732,7 @@ static void clear_dynamic_conf(void)

    else

     up = >next;

  }

+  daemon->dhcp_conf = NULL;

}

static void clear_dhcp_opt(struct dhcp_opt **dhcp_opts)

@@ -5755,8 +5756,10 @@ static void clear_dhcp_opt(struct dhcp_opt 
**dhcp_opts)


static void clear_dynamic_opt(void)

{

    clear_dhcp_opt(>dhcp_opts);

+  daemon->dhcp_opts = NULL;

#ifdef HAVE_DHCP6

    clear_dhcp_opt(>dhcp_opts6);

+  daemon->dhcp_opts6 = NULL;

#endif

}




This doesn't work. The daemon->dhcp_opts etc linked lists have a mixture 
of dynamic (re-readable) and static (from command line and dnsmasq.conf) 
entries. After clearing the re-readable entries, there may be static 
ones left in the linked list, so NULLing the pointers will leak those 
and stop them working.



Cheers,

Simon.


--

2.33.0


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[Dnsmasq-discuss] [PATCH] Set pointers to NULL after memory is freed

2023-10-08 Thread renmingshuai via Dnsmasq-discuss 
Set pointers to NULL after memory is freed to reduce dangling pointers, 
although they are later set to new values.

>From 5567d99099191f0cdb2922555e6ade2634f94f30 Mon Sep 17 00:00:00 2001
From: renmingshuai 
Date: Sun, 8 Oct 2023 16:06:46 +0800
Subject: [PATCH] Set pointers to NULL after memory is freed

---
src/option.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/src/option.c b/src/option.c
index 286f06b..23601e1 100644
--- a/src/option.c
+++ b/src/option.c
@@ -5732,6 +5732,7 @@ static void clear_dynamic_conf(void)
   else
up = >next;
 }
+  daemon->dhcp_conf = NULL;
}

static void clear_dhcp_opt(struct dhcp_opt **dhcp_opts)
@@ -5755,8 +5756,10 @@ static void clear_dhcp_opt(struct dhcp_opt **dhcp_opts)
static void clear_dynamic_opt(void)
{
   clear_dhcp_opt(>dhcp_opts);
+  daemon->dhcp_opts = NULL;
#ifdef HAVE_DHCP6
   clear_dhcp_opt(>dhcp_opts6);
+  daemon->dhcp_opts6 = NULL;
#endif
}

--
2.33.0
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