5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paolo Abeni pabeni@redhat.com
commit b6c620dc43ccb4e802894e54b651cf81495e9598 upstream.
When the MPTCP PM detects that a subflow is stale, all the packet scheduler must re-inject all the mptcp-level unacked data. To avoid acquiring unneeded locks, it first try to check if any unacked data is present at all in the RTX queue, but such check is currently broken, as it uses TCP-specific helper on an MPTCP socket.
Funnily enough fuzzers and static checkers are happy, as the accessed memory still belongs to the mptcp_sock struct, and even from a functional perspective the recovery completed successfully, as the short-cut test always failed.
A recent unrelated TCP change - commit d5fed5addb2b ("tcp: reorganize tcp_sock fast path variables") - exposed the issue, as the tcp field reorganization makes the mptcp code always skip the re-inection.
Fix the issue dropping the bogus call: we are on a slow path, the early optimization proved once again to be evil.
Fixes: 1e1d9d6f119c ("mptcp: handle pending data on closed subflow") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/468 Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://lore.kernel.org/r/20240131-upstream-net-20240131-mptcp-ci-issues-v1-... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 3 --- 1 file changed, 3 deletions(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2203,9 +2203,6 @@ bool __mptcp_retransmit_pending_data(str if (__mptcp_check_fallback(mptcp_sk(sk))) return false;
- if (tcp_rtx_and_write_queues_empty(sk)) - return false; - /* the closing socket has some data untransmitted and/or unacked: * some data in the mptcp rtx queue has not really xmitted yet. * keep it simple and re-inject the whole mptcp level rtx queue