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authorEric Dumazet <edumazet@google.com>2015-12-02 21:53:57 -0800
committerDavid S. Miller <davem@davemloft.net>2015-12-03 11:32:06 -0500
commit6bd4f355df2eae80b8a5c7b097371cd1e05f20d5 (patch)
treee903f55cdcc87ed834790e4f257d407f886a9d23 /net/ipv6/af_inet6.c
parentc836a8ba93869d6a0290a6ae0047fbef09066871 (diff)
downloadop-kernel-dev-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.zip
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ipv6: kill sk_dst_lock
While testing the np->opt RCU conversion, I found that UDP/IPv6 was using a mixture of xchg() and sk_dst_lock to protect concurrent changes to sk->sk_dst_cache, leading to possible corruptions and crashes. ip6_sk_dst_lookup_flow() uses sk_dst_check() anyway, so the simplest way to fix the mess is to remove sk_dst_lock completely, as we did for IPv4. __ip6_dst_store() and ip6_dst_store() share same implementation. sk_setup_caps() being called with socket lock being held or not, we have to use sk_dst_set() instead of __sk_dst_set() Note that I had to move the "np->dst_cookie = rt6_get_cookie(rt);" in ip6_dst_store() before the sk_setup_caps(sk, dst) call. This is because ip6_dst_store() can be called from process context, without any lock held. As soon as the dst is installed in sk->sk_dst_cache, dst can be freed from another cpu doing a concurrent ip6_dst_store() Doing the dst dereference before doing the install is needed to make sure no use after free would trigger. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/af_inet6.c')
-rw-r--r--net/ipv6/af_inet6.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 38d66dd..8ec0df7 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -673,7 +673,7 @@ int inet6_sk_rebuild_header(struct sock *sk)
return PTR_ERR(dst);
}
- __ip6_dst_store(sk, dst, NULL, NULL);
+ ip6_dst_store(sk, dst, NULL, NULL);
}
return 0;
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