Re: [PATCH net] ipvs: fix possible memory leak in ip_vs_control_net_init

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Thu, 19 Nov 2020, Wang Hai wrote:

> kmemleak report a memory leak as follows:
> 
> BUG: memory leak
> unreferenced object 0xffff8880759ea000 (size 256):
> comm "syz-executor.3", pid 6484, jiffies 4297476946 (age 48.546s)
> hex dump (first 32 bytes):
> 00 00 00 00 01 00 00 00 08 a0 9e 75 80 88 ff ff ...........u....
> 08 a0 9e 75 80 88 ff ff 00 00 00 00 ad 4e ad de ...u.........N..
> backtrace:
> [<00000000c0bf2deb>] kmem_cache_zalloc include/linux/slab.h:656 [inline]
> [<00000000c0bf2deb>] __proc_create+0x23d/0x7d0 fs/proc/generic.c:421
> [<000000009d718d02>] proc_create_reg+0x8e/0x140 fs/proc/generic.c:535
> [<0000000097bbfc4f>] proc_create_net_data+0x8c/0x1b0 fs/proc/proc_net.c:126
> [<00000000652480fc>] ip_vs_control_net_init+0x308/0x13a0 
> net/netfilter/ipvs/ip_vs_ctl.c:4169
> [<000000004c927ebe>] __ip_vs_init+0x211/0x400 
> net/netfilter/ipvs/ip_vs_core.c:2429
> [<00000000aa6b72d9>] ops_init+0xa8/0x3c0 net/core/net_namespace.c:151
> [<00000000153fd114>] setup_net+0x2de/0x7e0 net/core/net_namespace.c:341
> [<00000000be4e4f07>] copy_net_ns+0x27d/0x530 net/core/net_namespace.c:482
> [<00000000f1c23ec9>] create_new_namespaces+0x382/0xa30 kernel/nsproxy.c:110
> [<00000000098a5757>] copy_namespaces+0x2e6/0x3b0 kernel/nsproxy.c:179
> [<0000000026ce39e9>] copy_process+0x220a/0x5f00 kernel/fork.c:2072
> [<00000000b71f4efe>] _do_fork+0xc7/0xda0 kernel/fork.c:2428
> [<000000002974ee96>] __do_sys_clone3+0x18a/0x280 kernel/fork.c:2703
> [<0000000062ac0a4d>] do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
> [<0000000093f1ce2c>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> In the error path of ip_vs_control_net_init(), remove_proc_entry() needs
> to be called to remove the added proc entry, otherwise a memory leak
> will occur.
> 
> Fixes: b17fc9963f83 ("IPVS: netns, ip_vs_stats and its procfs")
> Fixes: 61b1ab4583e2 ("IPVS: netns, add basic init per netns.")
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_ctl.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index e279ded4e306..d99bb89e7c25 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -4180,6 +4180,9 @@ int __net_init ip_vs_control_net_init(struct netns_ipvs 
> *ipvs)
>       return 0;

        May be we should add some #ifdef CONFIG_PROC_FS because
proc_create_net* return NULL when PROC is not used. For example:

#ifdef CONFIG_PROC_FS
        if (!proc_create_net...
                goto err_vs;
        if (!proc_create_net...
                goto err_stats;
        ...
#endif
        ...

>  err:

#ifdef CONFIG_PROC_FS
> +     remove_proc_entry("ip_vs_stats_percpu", ipvs->net->proc_net);

err_percpu:
> +     remove_proc_entry("ip_vs_stats", ipvs->net->proc_net);

err_stats:
> +     remove_proc_entry("ip_vs", ipvs->net->proc_net);

err_vs:
#endif

>       free_percpu(ipvs->tot_stats.cpustats);
>       return -ENOMEM;
>  }
> -- 

Regards

--
Julian Anastasov <ja@xxxxxx>