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authorEric Dumazet <edumazet@google.com>2015-11-29 19:37:57 -0800
committerDavid S. Miller <davem@davemloft.net>2015-12-02 23:37:16 -0500
commit45f6fad84cc305103b28d73482b344d7f5b76f39 (patch)
tree283dbc3a6cd4a26288a3526d0de48cf8c2e27b75 /net/ipv6/datagram.c
parent01b3f52157ff5a47d6d8d796f396a4b34a53c61d (diff)
ipv6: add complete rcu protection around np->opt
This patch addresses multiple problems : UDP/RAW sendmsg() need to get a stable struct ipv6_txoptions while socket is not locked : Other threads can change np->opt concurrently. Dmitry posted a syzkaller (http://github.com/google/syzkaller) program desmonstrating use-after-free. Starting with TCP/DCCP lockless listeners, tcp_v6_syn_recv_sock() and dccp_v6_request_recv_sock() also need to use RCU protection to dereference np->opt once (before calling ipv6_dup_options()) This patch adds full RCU protection to np->opt Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/datagram.c')
-rw-r--r--net/ipv6/datagram.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index d70b0238f468..517c55b01ba8 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -167,8 +167,10 @@ ipv4_connected:
security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
- opt = flowlabel ? flowlabel->opt : np->opt;
+ rcu_read_lock();
+ opt = flowlabel ? flowlabel->opt : rcu_dereference(np->opt);
final_p = fl6_update_dst(&fl6, opt, &final);
+ rcu_read_unlock();
dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
err = 0;