| Message ID | 20240906145513.567781-1-andriy.shevchenko@linux.intel.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v1,1/1] netfilter: nf_reject: Fix build error when CONFIG_BRIDGE_NETFILTER=n | expand |
On Fri, Sep 06, 2024 at 05:55:13PM +0300, Andy Shevchenko wrote: > In some cases (CONFIG_BRIDGE_NETFILTER=n) the pointer to IP header > is set but not used, it prevents kernel builds with clang, `make W=1` > and CONFIG_WERROR=y: > > ipv6: split nf_send_reset6() in smaller functions > netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions > > net/ipv4/netfilter/nf_reject_ipv4.c:243:16: error: variable 'niph' set but not used [-Werror,-Wunused-but-set-variable] > 243 | struct iphdr *niph; > | ^ > net/ipv6/netfilter/nf_reject_ipv6.c:286:18: error: variable 'ip6h' set but not used [-Werror,-Wunused-but-set-variable] > 286 | struct ipv6hdr *ip6h; > | ^ > > Fix these by marking respective variables with __maybe_unused as it > seems more complicated to address that in a better way due to ifdeffery. > > Fixes: 8bfcdf6671b1 ("netfilter: nf_reject_ipv6: split nf_send_reset6() in smaller functions") > Fixes: 052b9498eea5 ("netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions") Hi Andy, As mentioned in relation to another similar patch, I'm not sure that resolution of W=1 warnings are fixes. > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > net/ipv4/netfilter/nf_reject_ipv4.c | 2 +- > net/ipv6/netfilter/nf_reject_ipv6.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c > index 04504b2b51df..0af42494ac66 100644 > --- a/net/ipv4/netfilter/nf_reject_ipv4.c > +++ b/net/ipv4/netfilter/nf_reject_ipv4.c > @@ -240,7 +240,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, > int hook) > { > struct sk_buff *nskb; > - struct iphdr *niph; > + struct iphdr *niph __maybe_unused; > const struct tcphdr *oth; > struct tcphdr _oth; > Possibly it is broken for some reason - like reading nskb too late - but I wonder if rather than annotating niph it's scope can be reduced to the code that is only compiled if CONFIG_BRIDGE_NETFILTER is enabled. This also addreses what appears to be an assingment of niph without the value being used - the first assingment. E.g., for the ipv4 case (compile tested only!): diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index 04504b2b51df..87fd945a0d27 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -239,9 +239,8 @@ static int nf_reject_fill_skb_dst(struct sk_buff *skb_in) void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, int hook) { - struct sk_buff *nskb; - struct iphdr *niph; const struct tcphdr *oth; + struct sk_buff *nskb; struct tcphdr _oth; oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); @@ -266,14 +265,12 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, nskb->mark = IP4_REPLY_MARK(net, oldskb->mark); skb_reserve(nskb, LL_MAX_HEADER); - niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, - ip4_dst_hoplimit(skb_dst(nskb))); + nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, + ip4_dst_hoplimit(skb_dst(nskb))); nf_reject_ip_tcphdr_put(nskb, oldskb, oth); if (ip_route_me_harder(net, sk, nskb, RTN_UNSPEC)) goto free_nskb; - niph = ip_hdr(nskb); - /* "Never happens" */ if (nskb->len > dst_mtu(skb_dst(nskb))) goto free_nskb; @@ -290,6 +287,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, */ if (nf_bridge_info_exists(oldskb)) { struct ethhdr *oeth = eth_hdr(oldskb); + struct iphdr *niph = ip_hdr(nskb); struct net_device *br_indev; br_indev = nf_bridge_get_physindev(oldskb, net);
On Sat, Sep 07, 2024 at 02:48:37PM +0100, Simon Horman wrote: > On Fri, Sep 06, 2024 at 05:55:13PM +0300, Andy Shevchenko wrote: > As mentioned in relation to another similar patch, > I'm not sure that resolution of W=1 warnings are fixes. Up to you, I consider they as fixes as I'm pretty much annoyed each release to have disable CONFIG_WERROR. But I got your point. ... > Possibly it is broken for some reason - like reading nskb too late - > but I wonder if rather than annotating niph it's scope can be reduced > to the code that is only compiled if CONFIG_BRIDGE_NETFILTER is enabled. > > This also addreses what appears to be an assingment of niph without > the value being used - the first assingment. > > E.g., for the ipv4 case (compile tested only!): Please, submit a formal patch, I'm not so familiar with the guts of networking core to be able to produce anything better than I already did. Consider this as Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Thank you!
Hi Simon, This proposed update to address this compile time warning LGTM. Would you submit it? Thanks. On Sat, Sep 07, 2024 at 02:48:37PM +0100, Simon Horman wrote: [...] > diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c > index 04504b2b51df..87fd945a0d27 100644 > --- a/net/ipv4/netfilter/nf_reject_ipv4.c > +++ b/net/ipv4/netfilter/nf_reject_ipv4.c > @@ -239,9 +239,8 @@ static int nf_reject_fill_skb_dst(struct sk_buff *skb_in) > void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, > int hook) > { > - struct sk_buff *nskb; > - struct iphdr *niph; > const struct tcphdr *oth; > + struct sk_buff *nskb; > struct tcphdr _oth; > > oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); > @@ -266,14 +265,12 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, > nskb->mark = IP4_REPLY_MARK(net, oldskb->mark); > > skb_reserve(nskb, LL_MAX_HEADER); > - niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, > - ip4_dst_hoplimit(skb_dst(nskb))); > + nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, > + ip4_dst_hoplimit(skb_dst(nskb))); > nf_reject_ip_tcphdr_put(nskb, oldskb, oth); > if (ip_route_me_harder(net, sk, nskb, RTN_UNSPEC)) > goto free_nskb; > > - niph = ip_hdr(nskb); > - > /* "Never happens" */ > if (nskb->len > dst_mtu(skb_dst(nskb))) > goto free_nskb; > @@ -290,6 +287,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, > */ > if (nf_bridge_info_exists(oldskb)) { > struct ethhdr *oeth = eth_hdr(oldskb); > + struct iphdr *niph = ip_hdr(nskb); > struct net_device *br_indev; > > br_indev = nf_bridge_get_physindev(oldskb, net);
On Sun, Sep 15, 2024 at 11:22:02PM +0200, Pablo Neira Ayuso wrote: > Hi Simon, > > This proposed update to address this compile time warning LGTM. > > Would you submit it? Hi Pablo, Yes, it is on my todo list for today. Sorry for not getting to it sooner. I plan to post a patch for this to nf-next. But let me know if you prefer a patch for nf, net, or some other course of action.
On Mon, Sep 16, 2024 at 08:32:01AM +0100, Simon Horman wrote: > On Sun, Sep 15, 2024 at 11:22:02PM +0200, Pablo Neira Ayuso wrote: > > Hi Simon, > > > > This proposed update to address this compile time warning LGTM. > > > > Would you submit it? > > Hi Pablo, > > Yes, it is on my todo list for today. > Sorry for not getting to it sooner. > > I plan to post a patch for this to nf-next. > But let me know if you prefer a patch for nf, net, > or some other course of action. Patch posted here: - [PATCH nf-next] netfilter: nf_reject: Fix build warning when CONFIG_BRIDGE_NETFILTER=n https://lore.kernel.org/netfilter-devel/20240916-nf-reject-v1-1-24b6dd651c83@kernel.org/
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index 04504b2b51df..0af42494ac66 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -240,7 +240,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, int hook) { struct sk_buff *nskb; - struct iphdr *niph; + struct iphdr *niph __maybe_unused; const struct tcphdr *oth; struct tcphdr _oth; diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c index dedee264b8f6..f5ed4e779b72 100644 --- a/net/ipv6/netfilter/nf_reject_ipv6.c +++ b/net/ipv6/netfilter/nf_reject_ipv6.c @@ -283,7 +283,7 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb, const struct tcphdr *otcph; unsigned int otcplen, hh_len; const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); - struct ipv6hdr *ip6h; + struct ipv6hdr *ip6h __maybe_unused; struct dst_entry *dst = NULL; struct flowi6 fl6;
In some cases (CONFIG_BRIDGE_NETFILTER=n) the pointer to IP header is set but not used, it prevents kernel builds with clang, `make W=1` and CONFIG_WERROR=y: ipv6: split nf_send_reset6() in smaller functions netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions net/ipv4/netfilter/nf_reject_ipv4.c:243:16: error: variable 'niph' set but not used [-Werror,-Wunused-but-set-variable] 243 | struct iphdr *niph; | ^ net/ipv6/netfilter/nf_reject_ipv6.c:286:18: error: variable 'ip6h' set but not used [-Werror,-Wunused-but-set-variable] 286 | struct ipv6hdr *ip6h; | ^ Fix these by marking respective variables with __maybe_unused as it seems more complicated to address that in a better way due to ifdeffery. Fixes: 8bfcdf6671b1 ("netfilter: nf_reject_ipv6: split nf_send_reset6() in smaller functions") Fixes: 052b9498eea5 ("netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions") Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- net/ipv4/netfilter/nf_reject_ipv4.c | 2 +- net/ipv6/netfilter/nf_reject_ipv6.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)