ipv6: add rcu grace period before freeing fib6_node
authorWei Wang <weiwan@google.com>
Mon, 21 Aug 2017 16:47:10 +0000 (09:47 -0700)
committerDavid S. Miller <davem@davemloft.net>
Tue, 22 Aug 2017 18:03:19 +0000 (11:03 -0700)
commitc5cff8561d2d0006e972bd114afd51f082fee77c
tree590d33658f2a4a6add9db5734988b80a5313efc8
parent0c8d2d95b815c7610720b7e868b395a019864720
ipv6: add rcu grace period before freeing fib6_node

We currently keep rt->rt6i_node pointing to the fib6_node for the route.
And some functions make use of this pointer to dereference the fib6_node
from rt structure, e.g. rt6_check(). However, as there is neither
refcount nor rcu taken when dereferencing rt->rt6i_node, it could
potentially cause crashes as rt->rt6i_node could be set to NULL by other
CPUs when doing a route deletion.
This patch introduces an rcu grace period before freeing fib6_node and
makes sure the functions that dereference it takes rcu_read_lock().

Note: there is no "Fixes" tag because this bug was there in a very
early stage.

Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/ip6_fib.h
net/ipv6/ip6_fib.c
net/ipv6/route.c