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author | Eric Dumazet <edumazet@google.com> | 2015-12-03 06:53:57 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-12-03 17:32:06 +0100 |
commit | 6bd4f355df2eae80b8a5c7b097371cd1e05f20d5 (patch) | |
tree | e903f55cdcc87ed834790e4f257d407f886a9d23 /net/ipv6/af_inet6.c | |
parent | ipv6: sctp: add rcu protection around np->opt (diff) | |
download | linux-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.tar.xz linux-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.zip |
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.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 38d66ddfb937..8ec0df75f1c4 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; |