From 247488c0a490214a0b5227a678ec2d46b7dba4e5 Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Fri, 16 Jun 2017 10:46:37 -0700 Subject: [PATCH] decnet: always not take dst->__refcnt when inserting dst into hash table In the existing dn_route.c code, dn_route_output_slow() takes dst->__refcnt before calling dn_insert_route() while dn_route_input_slow() does not take dst->__refcnt before calling dn_insert_route(). This makes the whole routing code very buggy. In dn_dst_check_expire(), dnrt_free() is called when rt expires. This makes the routes inserted by dn_route_output_slow() not able to be freed as the refcnt is not released. In dn_dst_gc(), dnrt_drop() is called to release rt which could potentially cause the dst->__refcnt to be dropped to -1. In dn_run_flush(), dst_free() is called to release all the dst. Again, it makes the dst inserted by dn_route_output_slow() not able to be released and also, it does not wait on the rcu and could potentially cause crash in the path where other users still refer to this dst. This patch makes sure both input and output path do not take dst->__refcnt before calling dn_insert_route() and also makes sure dnrt_free()/dst_free() is called when removing dst from the hash table. The only difference between those 2 calls is that dnrt_free() waits on the rcu while dst_free() does not. Signed-off-by: Wei Wang Acked-by: Martin KaFai Lau Signed-off-by: David S. Miller --- net/decnet/dn_route.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c index 4b9518a..6f95612 100644 --- a/net/decnet/dn_route.c +++ b/net/decnet/dn_route.c @@ -188,12 +188,6 @@ static inline void dnrt_free(struct dn_route *rt) call_rcu_bh(&rt->dst.rcu_head, dst_rcu_free); } -static inline void dnrt_drop(struct dn_route *rt) -{ - dst_release(&rt->dst); - call_rcu_bh(&rt->dst.rcu_head, dst_rcu_free); -} - static void dn_dst_check_expire(unsigned long dummy) { int i; @@ -248,7 +242,7 @@ static int dn_dst_gc(struct dst_ops *ops) } *rtp = rt->dst.dn_next; rt->dst.dn_next = NULL; - dnrt_drop(rt); + dnrt_free(rt); break; } spin_unlock_bh(&dn_rt_hash_table[i].lock); @@ -350,7 +344,7 @@ static int dn_insert_route(struct dn_route *rt, unsigned int hash, struct dn_rou dst_use(&rth->dst, now); spin_unlock_bh(&dn_rt_hash_table[hash].lock); - dnrt_drop(rt); + dst_free(&rt->dst); *rp = rth; return 0; } @@ -380,7 +374,7 @@ static void dn_run_flush(unsigned long dummy) for(; rt; rt = next) { next = rcu_dereference_raw(rt->dst.dn_next); RCU_INIT_POINTER(rt->dst.dn_next, NULL); - dst_free((struct dst_entry *)rt); + dnrt_free(rt); } nothing_to_declare: @@ -1187,7 +1181,7 @@ make_route: if (dev_out->flags & IFF_LOOPBACK) flags |= RTCF_LOCAL; - rt = dst_alloc(&dn_dst_ops, dev_out, 1, DST_OBSOLETE_NONE, DST_HOST); + rt = dst_alloc(&dn_dst_ops, dev_out, 0, DST_OBSOLETE_NONE, DST_HOST); if (rt == NULL) goto e_nobufs; -- 2.7.4