diff options
| author | Paolo Abeni <pabeni@redhat.com> | 2023-03-09 15:49:57 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-22 13:34:02 +0100 |
| commit | f76e08cf98aa11afb5cdc27a49a1136bd22bb1b0 (patch) | |
| tree | e7b3761c974d027fae200b17feafccaad276cae4 /net/mptcp | |
| parent | 39374fc8bb11990ed69348bfe517d3df0463b263 (diff) | |
| download | linux-stable-f76e08cf98aa11afb5cdc27a49a1136bd22bb1b0.tar.gz linux-stable-f76e08cf98aa11afb5cdc27a49a1136bd22bb1b0.tar.bz2 linux-stable-f76e08cf98aa11afb5cdc27a49a1136bd22bb1b0.zip | |
mptcp: fix possible deadlock in subflow_error_report
commit b7a679ba7c652587b85294f4953f33ac0b756d40 upstream.
Christoph reported a possible deadlock while the TCP stack
destroys an unaccepted subflow due to an incoming reset: the
MPTCP socket error path tries to acquire the msk-level socket
lock while TCP still owns the listener socket accept queue
spinlock, and the reverse dependency already exists in the
TCP stack.
Note that the above is actually a lockdep false positive, as
the chain involves two separate sockets. A different per-socket
lockdep key will address the issue, but such a change will be
quite invasive.
Instead, we can simply stop earlier the socket error handling
for orphaned or unaccepted subflows, breaking the critical
lockdep chain. Error handling in such a scenario is a no-op.
Reported-and-tested-by: Christoph Paasch <cpaasch@apple.com>
Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/355
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/mptcp')
| -rw-r--r-- | net/mptcp/subflow.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index c4971bc42f60..0bbaf26500e9 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1376,6 +1376,13 @@ static void subflow_error_report(struct sock *ssk) { struct sock *sk = mptcp_subflow_ctx(ssk)->conn; + /* bail early if this is a no-op, so that we avoid introducing a + * problematic lockdep dependency between TCP accept queue lock + * and msk socket spinlock + */ + if (!sk->sk_socket) + return; + mptcp_data_lock(sk); if (!sock_owned_by_user(sk)) __mptcp_error_report(sk); |