Patchwork netfilter, ipvs: Avoid undefined order of evaluation in assignments to struct nf_conn *

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Submitter Jesper Juhl
Date May 29, 2011, 6:22 p.m.
Message ID <alpine.LNX.2.00.1105292011450.4411@swampdragon.chaosbits.net>
Download mbox | patch
Permalink /patch/97848/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Jesper Juhl - May 29, 2011, 6:22 p.m.
In net/netfilter/ipvs/ip_vs_nfct.c::ip_vs_update_conntrack(),
net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_nat_xmit(), 
net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_nat_xmit_v6(), 
net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_icmp_xmit)() 
net/netfilter/ipvs/ip_vs_xmit.c::and ip_vs_icmp_xmit_v6() we do this:
	...
	struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
	...

Since '=' is not a sequence point the order of these assignments happening 
is undefined. Luckily it's easy to avoid by just doing what is obviously 
the intended thing:
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
---
 ip_vs_nfct.c |    2 +-
 ip_vs_xmit.c |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

 Compile tested only.
 Patch is against Linus' tree as of a few minutes ago.
Simon Horman - May 29, 2011, 11:23 p.m.
On Sun, May 29, 2011 at 08:22:56PM +0200, Jesper Juhl wrote:
> In net/netfilter/ipvs/ip_vs_nfct.c::ip_vs_update_conntrack(),
> net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_nat_xmit(), 
> net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_nat_xmit_v6(), 
> net/netfilter/ipvs/ip_vs_xmit.c::ip_vs_icmp_xmit)() 
> net/netfilter/ipvs/ip_vs_xmit.c::and ip_vs_icmp_xmit_v6() we do this:
> 	...
> 	struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
> 	...
> 
> Since '=' is not a sequence point the order of these assignments happening 
> is undefined. Luckily it's easy to avoid by just doing what is obviously 
> the intended thing:
> 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
> 
> Signed-off-by: Jesper Juhl <jj@chaosbits.net>

Acked-by: Simon Horman <horms@verge.net.au>
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Pablo Neira - June 2, 2011, 12:59 p.m.
On 30/05/11 01:23, Simon Horman wrote:
> Acked-by: Simon Horman <horms@verge.net.au>

applied, thanks
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Patch

diff --git a/net/netfilter/ipvs/ip_vs_nfct.c b/net/netfilter/ipvs/ip_vs_nfct.c
index f454c80..a3d86c2 100644
--- a/net/netfilter/ipvs/ip_vs_nfct.c
+++ b/net/netfilter/ipvs/ip_vs_nfct.c
@@ -82,7 +82,7 @@  void
 ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin)
 {
 	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 	struct nf_conntrack_tuple new_tuple;
 
 	if (ct == NULL || nf_ct_is_confirmed(ct) || nf_ct_is_untracked(ct) ||
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index ee319a4..16d129e 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -544,7 +544,7 @@  ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
 		enum ip_conntrack_info ctinfo;
-		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 
 		if (ct && !nf_ct_is_untracked(ct)) {
 			IP_VS_DBG_RL_PKT(10, AF_INET, pp, skb, 0,
@@ -661,7 +661,7 @@  ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
 		enum ip_conntrack_info ctinfo;
-		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 
 		if (ct && !nf_ct_is_untracked(ct)) {
 			IP_VS_DBG_RL_PKT(10, AF_INET6, pp, skb, 0,
@@ -1176,7 +1176,7 @@  ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
 		enum ip_conntrack_info ctinfo;
-		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 
 		if (ct && !nf_ct_is_untracked(ct)) {
 			IP_VS_DBG(10, "%s(): "
@@ -1296,7 +1296,7 @@  ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	if (cp->flags & IP_VS_CONN_F_SYNC && local) {
 		enum ip_conntrack_info ctinfo;
-		struct nf_conn *ct = ct = nf_ct_get(skb, &ctinfo);
+		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 
 		if (ct && !nf_ct_is_untracked(ct)) {
 			IP_VS_DBG(10, "%s(): "