ipv6: check fn->leaf before it is used

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If rwlock is replaced with rcu and spinlock, it is possible that the
reader thread will see fn->leaf as NULL in the following scenarios:
1. fib6_add() is in progress and we have already inserted a new node but
not yet inserted the route.
2. fib6_del_route() is in progress and we have already set fn->leaf to
NULL but not yet freed the node because of rcu grace period.

This patch makes sure all the reader threads check fn->leaf first before
using it. And together with later patch to grab rcu_read_lock() and
rcu_dereference() fn->leaf, it makes sure reader threads are safe when
accessing fn->leaf.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

...

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Wei Wang 2017-10-06 12:06:08 -07:00 • committed by David S. Miller

parent bbd63f06d1

commit 8d1040e808

2 changed files with 30 additions and 13 deletions

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23

net/ipv6/ip6_fib.c

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20

net/ipv6/route.c

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