[PATCH nf] netfilter: nf_expect_proc: remove the redundant slash when policy name is empty

[PATCH nf] netfilter: nf_expect_proc: remove the redundant slash when policy name is empty

[Liping Zhang]

From: Liping Zhang <liping.zhang@spreadtrum.com>

The 'name' filed in struct nf_conntrack_expect_policy{} is not a
pointer, so check it is NULL or not will always return true. Even if the
name is empty, slash will always be displayed like follows:
  # cat /proc/net/nf_conntrack_expect
  297 l3proto = 2 proto=6 src=1.1.1.1 dst=2.2.2.2 sport=1 dport=1025 ftp/
                                                                        ^

Fixes: 3a8fc53a45c4 ("netfilter: nf_ct_helper: allocate 16 bytes for the helper and policy names")
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
---
 net/netfilter/nf_conntrack_expect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index 9e36931..a4f3cc8 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -574,7 +574,7 @@ static int exp_seq_show(struct seq_file *s, void *v)
 	helper = rcu_dereference(nfct_help(expect->master)->helper);
 	if (helper) {
 		seq_printf(s, "%s%s", expect->flags ? " " : "", helper->name);
-		if (helper->expect_policy[expect->class].name)
+		if (helper->expect_policy[expect->class].name[0] != '\0')
 			seq_printf(s, "/%s",
 				   helper->expect_policy[expect->class].name);
 	}
-- 
2.5.5

Re: [PATCH nf] netfilter: nf_expect_proc: remove the redundant slash when policy name is empty

[Pablo Neira Ayuso]

On Mon, Aug 08, 2016 at 09:57:58PM +0800, Liping Zhang wrote:
> From: Liping Zhang <liping.zhang@spreadtrum.com>
> 
> The 'name' filed in struct nf_conntrack_expect_policy{} is not a
> pointer, so check it is NULL or not will always return true. Even if the
> name is empty, slash will always be displayed like follows:
>   # cat /proc/net/nf_conntrack_expect
>   297 l3proto = 2 proto=6 src=1.1.1.1 dst=2.2.2.2 sport=1 dport=1025 ftp/
>                                                                         ^
> 
> Fixes: 3a8fc53a45c4 ("netfilter: nf_ct_helper: allocate 16 bytes for the helper and policy names")
> Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
> ---
>  net/netfilter/nf_conntrack_expect.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
> index 9e36931..a4f3cc8 100644
> --- a/net/netfilter/nf_conntrack_expect.c
> +++ b/net/netfilter/nf_conntrack_expect.c
> @@ -574,7 +574,7 @@ static int exp_seq_show(struct seq_file *s, void *v)
>  	helper = rcu_dereference(nfct_help(expect->master)->helper);
>  	if (helper) {
>  		seq_printf(s, "%s%s", expect->flags ? " " : "", helper->name);
> -		if (helper->expect_policy[expect->class].name)
> +		if (helper->expect_policy[expect->class].name[0] != '\0')

Good catch. I can simplify this here to:

                if (helper->expect_policy[expect->class].name[0])

We use similar idiom in other locations in the netfilter code. No need
to resend if OK with it.