[PATCH v2 1/2 nf-next] netfilter: ftp: Remove the useless dlen==0 condition check in find_pattern

[PATCH v2 1/2 nf-next] netfilter: ftp: Remove the useless dlen==0 condition check in find_pattern

[fgao]

From: Gao Feng <fgao@ikuai8.com>

The caller function "help" has already make sure the datalen could not be zero
before invoke find_pattern as a parameter by the following codes

        if (dataoff >= skb->len) {
                pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
                         skb->len);
                return NF_ACCEPT;
        }
        datalen = skb->len - dataoff;

And the latter codes "ends_in_nl = (fb_ptr[datalen - 1] == '\n');" use datalen
directly without checking if it is zero.

So it is unneccessary to check it in find_pattern too.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
---
 v2: Split original patch to two commits;
 v1: Initial patch

 net/netfilter/nf_conntrack_ftp.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index b6934b5..d49a2d4 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -301,8 +301,6 @@ static int find_pattern(const char *data, size_t dlen,
 	size_t i = plen;
 
 	pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen);
-	if (dlen == 0)
-		return 0;
 
 	if (dlen <= plen) {
 		/* Short packet: try for partial? */
-- 
1.9.1

Re: [PATCH v2 1/2 nf-next] netfilter: ftp: Remove the useless dlen==0 condition check in find_pattern

[Pablo Neira Ayuso]

On Thu, Sep 01, 2016 at 06:58:29PM +0800, fgao@ikuai8.com wrote:
> From: Gao Feng <fgao@ikuai8.com>
> 
> The caller function "help" has already make sure the datalen could not be zero
> before invoke find_pattern as a parameter by the following codes
> 
>         if (dataoff >= skb->len) {
>                 pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
>                          skb->len);
>                 return NF_ACCEPT;
>         }
>         datalen = skb->len - dataoff;
> 
> And the latter codes "ends_in_nl = (fb_ptr[datalen - 1] == '\n');" use datalen
> directly without checking if it is zero.
>
> So it is unneccessary to check it in find_pattern too.

Applied, thanks.