From: Florian Westphal fw@strlen.de
[ Upstream commit 17aee05dc8822e354f5ad2d68ee39e3ba4b6acf2 ]
Christoph Paasch reported following crash: dst_release underflow WARNING: CPU: 0 PID: 1319 at net/core/dst.c:175 dst_release+0xc1/0xd0 net/core/dst.c:175 CPU: 0 PID: 1319 Comm: syz-executor217 Not tainted 5.11.0-rc6af8e85128b4d0d24083c5cac646e891227052e0c #70 Call Trace: rt_cache_route+0x12e/0x140 net/ipv4/route.c:1503 rt_set_nexthop.constprop.0+0x1fc/0x590 net/ipv4/route.c:1612 __mkroute_output net/ipv4/route.c:2484 [inline] ...
The worker leaves msk->subflow alone even when it happened to close the subflow ssk associated with it.
Fixes: 866f26f2a9c33b ("mptcp: always graft subflow socket to parent") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/157 Reported-by: Christoph Paasch cpaasch@apple.com Suggested-by: Paolo Abeni pabeni@redhat.com Acked-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Mat Martineau mathew.j.martineau@linux.intel.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/mptcp/protocol.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 64b8a49652ae..7345df40385a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2100,6 +2100,14 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) return backup; }
+static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk) +{ + if (msk->subflow) { + iput(SOCK_INODE(msk->subflow)); + msk->subflow = NULL; + } +} + /* subflow sockets can be either outgoing (connect) or incoming * (accept). * @@ -2144,6 +2152,9 @@ void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
if (ssk == msk->last_snd) msk->last_snd = NULL; + + if (msk->subflow && ssk == msk->subflow->sk) + mptcp_dispose_initial_subflow(msk); }
static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu) @@ -2533,12 +2544,6 @@ static void __mptcp_destroy_sock(struct sock *sk)
might_sleep();
- /* dispose the ancillatory tcp socket, if any */ - if (msk->subflow) { - iput(SOCK_INODE(msk->subflow)); - msk->subflow = NULL; - } - /* be sure to always acquire the join list lock, to sync vs * mptcp_finish_join(). */ @@ -2563,6 +2568,7 @@ static void __mptcp_destroy_sock(struct sock *sk) sk_stream_kill_queues(sk); xfrm_sk_free_policy(sk); sk_refcnt_debug_release(sk); + mptcp_dispose_initial_subflow(msk); sock_put(sk); }