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| author | Eric Dumazet <edumazet@google.com> | 2015-12-02 21:53:57 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-12-03 11:32:06 -0500 |
| commit | 6bd4f355df2eae80b8a5c7b097371cd1e05f20d5 (patch) | |
| tree | e903f55cdcc87ed834790e4f257d407f886a9d23 /include/net/sock.h | |
| parent | c836a8ba93869d6a0290a6ae0047fbef09066871 (diff) | |
| download | linux-0-day-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.tar.gz linux-0-day-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.tar.xz | |
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 'include/net/sock.h')
| -rw-r--r-- | include/net/sock.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 0434138c5f952..52d27ee924f47 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -254,7 +254,6 @@ struct cg_proto; * @sk_wq: sock wait queue and async head * @sk_rx_dst: receive input route used by early demux * @sk_dst_cache: destination cache - * @sk_dst_lock: destination cache lock * @sk_policy: flow policy * @sk_receive_queue: incoming packets * @sk_wmem_alloc: transmit queue bytes committed @@ -393,7 +392,7 @@ struct sock { #endif struct dst_entry *sk_rx_dst; struct dst_entry __rcu *sk_dst_cache; - spinlock_t sk_dst_lock; + /* Note: 32bit hole on 64bit arches */ atomic_t sk_wmem_alloc; atomic_t sk_omem_alloc; int sk_sndbuf; |