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ipv6: fix a dst leak when removing its exception 

These is no need to hold dst before calling rt6_remove_exception_rt().
The call to dst_hold_safe() in ip6_link_failure() was for ip6_del_rt(),
which has been removed in Commit 93531c6743 ("net/ipv6: separate
handling of FIB entries from dst based routes"). Otherwise, it will
cause a dst leak.

This patch is to simply remove the dst_hold_safe() call before calling
rt6_remove_exception_rt() and also do the same in ip6_del_cached_rt().
It's safe, because the removal of the exception that holds its dst's
refcnt is protected by rt6_exception_lock.

Fixes: 93531c6743 ("net/ipv6: separate handling of FIB entries from dst based routes")
Fixes: 23fb93a4d3 ("net/ipv6: Cleanup exception and cache route handling")
Reported-by: Li Shuang <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2018-11-14 00:48:28 +08:00 committed by David S. Miller
parent 83e65df6df
commit 761f60261b
1 changed files with 3 additions and 4 deletions
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3
net/ipv6/route.c
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@ -2232,7 +2232,6 @@ static void ip6_link_failure(struct sk_buff *skb)
if (rt) {
rcu_read_lock();
if (rt->rt6i_flags & RTF_CACHE) {
if (dst_hold_safe(&rt->dst))
rt6_remove_exception_rt(rt);
} else {
struct fib6_info *from;
@ -3214,7 +3213,7 @@ static int ip6_del_cached_rt(struct rt6_info *rt, struct fib6_config *cfg)
if (cfg->fc_flags & RTF_GATEWAY &&
!ipv6_addr_equal(&cfg->fc_gateway, &rt->rt6i_gateway))
goto out;
if (dst_hold_safe(&rt->dst))
rc = rt6_remove_exception_rt(rt);
out:
return rc;