[Dnsmasq-discuss] [PATCH] Fix DHCPv6 options memory leaks

[Geert Stappers]

On Thu, Sep 28, 2023 at 08:28:35AM +0000, renmingshuai via Dnsmasq-discuss wrote:
> When I repeatedly reloaded the dnsmasq process, I found a memory
> leak. To reproduce the problem, perform the following steps:
> 
> (1)   Run dnsmasq as follows:
> # dnsmasq --no-hosts --no-resolv --dhcp-optsfile=/tmp/opts --dhcp-range=set:subnetUUID,2003:0:0:1499::,static,64,2h
> # cat /tmp/opts
> tag:subnetUUID,option6:domain-search,openstacklocal
> tag:subnetUUID,option6:dns-server,[2003:0:0:1499::2],[2003:0:0:1499::3]
> 
> (2)    Send SIGHUP to dnsmasq repeatedly
> # cat send.sh
> #!/bin/bash
> while true
> do
>        kill -HUP `pidof dnsmasq`
>        sleep

sleep: missing operand


> done
> # sh send.sh
> 
> After a period of time, the vmRss value of the dnsmasq process keeps increasing.
> 
> # date
> Fri Sep 29 12:43:27 AM CST 2023
> [root at localhost home]# ps -aux|grep dnsmasq
> dnsmasq  3322571  0.0  0.0   9044  2456 ?        S    00:43   0:00 dnsmasq --no-hosts --no-resolv --dhcp-optsfile=/tmp/opts --dhcp-range=set:subnetUUID,2003:0:0:1499::,static,64,infinite
> # date
> Fri Sep 29 01:09:28 AM CST 2023
> # ps -aux|grep dnsmasq
> dnsmasq  3322571  0.1  0.0   9772  3280 ?        S    00:43   0:02 dnsmasq --no-hosts --no-resolv --dhcp-optsfile=/tmp/opts --dhcp-range=set:subnetUUID,2003:0:0:1499::,static,64,infinite
> 
> When we configure DHCPv6 option information by using -dhcp-optsfile,
> dnsmasq process allocates memory to store those information. However,
> when dnsmasq receives SIGHUP and reread the -dhcp-optsfile, it does
> not release the memory that store DHCPv6 options information as it
> does for DHCPv4 options.
> 
> The following patch could fix this problem.
> ---
> src/option.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/option.c b/src/option.c
> index 8322725..1cf2796 100644
> --- a/src/option.c
> +++ b/src/option.c
> @@ -5734,11 +5734,11 @@ static void clear_dynamic_conf(void)
>      }
> }
> -static void clear_dynamic_opt(void)
> +static void clear_dhcp_opt(struct dhcp_opt **dhcp_opts)
> {
>    struct dhcp_opt *opts, *cp, **up;
> -  for (up = &daemon->dhcp_opts, opts = daemon->dhcp_opts; opts; opts = cp)
> +  for (up = dhcp_opts, opts = *dhcp_opts; opts; opts = cp)
>      {
>        cp = opts->next;
> 
> @@ -5752,6 +5752,14 @@ static void clear_dynamic_opt(void)
>      }
> }
> +static void clear_dynamic_opt(void)
> +{
> +  clear_dhcp_opt(&daemon->dhcp_opts);
> +#ifdef HAVE_DHCP6
> +  clear_dhcp_opt(&daemon->dhcp_opts6);
> +#endif
> +}
> +
> void reread_dhcp(void)
> {
>     struct hostsfile *hf;
> --
> 2.33.0


That looks good to me.  However:
|$ git am
|Applying: Fix DHCPv6 options memory leaks
|error: corrupt patch at line 11
|Patch failed at 0001 Fix DHCPv6 options memory leaks
|hint: Use 'git am --show-current-patch=diff' to see the failed patch
|When you have resolved this problem, run "git am --continue".
|If you prefer to skip this patch, run "git am --skip" instead.
|To restore the original branch and stop patching, run "git am --abort".
|$ 

See https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2023q3/017238.html
and make another attempt.



Groeten
Geert Stappers
-- 
Silence is hard to parse