From ce723d8e048ef98ea64d12379e3921c933f5b3e0 Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Thu, 8 Sep 2005 13:34:47 -0700 Subject: [PATCH] [IPV4]: Fix refcount damaging in net/ipv4/route.c One such place that can damage the dst refcnts is route.c with CONFIG_IP_ROUTE_MULTIPATH_CACHED enabled, i don't see the user's .config. In this new code i see that rt_intern_hash is called before dst->refcnt is set to 1, dst is the 2nd arg to rt_intern_hash. Arg 2 of rt_intern_hash must come with refcnt 1 as it is added to table or dropped depending on error/add/update. One such example is ip_mkroute_input where __mkroute_input return rth with refcnt 0 which is provided to rt_intern_hash. ip_mkroute_output looks like a 2nd such place. Appending untested patch for comments and review. The idea is to put previous reference as we are going to return next result/error. Signed-off-by: Julian Anastasov Signed-off-by: David S. Miller --- net/ipv4/route.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8c0b14e3beec..8549f26e2495 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1760,6 +1760,7 @@ static inline int __mkroute_input(struct sk_buff *skb, goto cleanup; } + atomic_set(&rth->u.dst.__refcnt, 1); rth->u.dst.flags= DST_HOST; #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED if (res->fi->fib_nhs > 1) @@ -1820,7 +1821,6 @@ static inline int ip_mkroute_input_def(struct sk_buff *skb, err = __mkroute_input(skb, res, in_dev, daddr, saddr, tos, &rth); if (err) return err; - atomic_set(&rth->u.dst.__refcnt, 1); /* put it into the cache */ hash = rt_hash_code(daddr, saddr ^ (fl->iif << 5), tos); @@ -1834,8 +1834,8 @@ static inline int ip_mkroute_input(struct sk_buff *skb, u32 daddr, u32 saddr, u32 tos) { #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED - struct rtable* rth = NULL; - unsigned char hop, hopcount, lasthop; + struct rtable* rth = NULL, *rtres; + unsigned char hop, hopcount; int err = -EINVAL; unsigned int hash; @@ -1844,8 +1844,6 @@ static inline int ip_mkroute_input(struct sk_buff *skb, else hopcount = 1; - lasthop = hopcount - 1; - /* distinguish between multipath and singlepath */ if (hopcount < 2) return ip_mkroute_input_def(skb, res, fl, in_dev, daddr, @@ -1855,6 +1853,10 @@ static inline int ip_mkroute_input(struct sk_buff *skb, for (hop = 0; hop < hopcount; hop++) { res->nh_sel = hop; + /* put reference to previous result */ + if (hop) + ip_rt_put(rtres); + /* create a routing cache entry */ err = __mkroute_input(skb, res, in_dev, daddr, saddr, tos, &rth); @@ -1863,7 +1865,7 @@ static inline int ip_mkroute_input(struct sk_buff *skb, /* put it into the cache */ hash = rt_hash_code(daddr, saddr ^ (fl->iif << 5), tos); - err = rt_intern_hash(hash, rth, (struct rtable**)&skb->dst); + err = rt_intern_hash(hash, rth, &rtres); if (err) return err; @@ -1873,13 +1875,8 @@ static inline int ip_mkroute_input(struct sk_buff *skb, FIB_RES_NETMASK(*res), res->prefixlen, &FIB_RES_NH(*res)); - - /* only for the last hop the reference count is handled - * outside - */ - if (hop == lasthop) - atomic_set(&(skb->dst->__refcnt), 1); } + skb->dst = &rtres->u.dst; return err; #else /* CONFIG_IP_ROUTE_MULTIPATH_CACHED */ return ip_mkroute_input_def(skb, res, fl, in_dev, daddr, saddr, tos); @@ -2208,6 +2205,7 @@ static inline int __mkroute_output(struct rtable **result, goto cleanup; } + atomic_set(&rth->u.dst.__refcnt, 1); rth->u.dst.flags= DST_HOST; #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED if (res->fi) { @@ -2290,8 +2288,6 @@ static inline int ip_mkroute_output_def(struct rtable **rp, if (err == 0) { u32 tos = RT_FL_TOS(oldflp); - atomic_set(&rth->u.dst.__refcnt, 1); - hash = rt_hash_code(oldflp->fl4_dst, oldflp->fl4_src ^ (oldflp->oif << 5), tos); err = rt_intern_hash(hash, rth, rp); @@ -2326,6 +2322,10 @@ static inline int ip_mkroute_output(struct rtable** rp, dev2nexthop = FIB_RES_DEV(*res); dev_hold(dev2nexthop); + /* put reference to previous result */ + if (hop) + ip_rt_put(*rp); + err = __mkroute_output(&rth, res, fl, oldflp, dev2nexthop, flags); @@ -2350,7 +2350,6 @@ static inline int ip_mkroute_output(struct rtable** rp, if (err != 0) return err; } - atomic_set(&(*rp)->u.dst.__refcnt, 1); return err; } else { return ip_mkroute_output_def(rp, res, fl, oldflp, dev_out, -- 2.30.2