6.10-stable review patch. If anyone has any objections, please let me know.
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From: Matthieu Baerts (NGI0) matttbe@kernel.org
commit 1c1f721375989579e46741f59523e39ec9b2a9bd upstream.
Adding the following warning ...
WARN_ON_ONCE(msk->pm.add_addr_accepted == 0)
... before decrementing the add_addr_accepted counter helped to find a bug when running the "remove single subflow" subtest from the mptcp_join.sh selftest.
Removing a 'subflow' endpoint will first trigger a RM_ADDR, then the subflow closure. Before this patch, and upon the reception of the RM_ADDR, the other peer will then try to decrement this add_addr_accepted. That's not correct because the attached subflows have not been created upon the reception of an ADD_ADDR.
A way to solve that is to decrement the counter only if the attached subflow was an MP_JOIN to a remote id that was not 0, and initiated by the host receiving the RM_ADDR.
Fixes: d0876b2284cf ("mptcp: add the incoming RM_ADDR support") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-9-38035d40de5b@... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/pm_netlink.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -829,7 +829,7 @@ static void mptcp_pm_nl_rm_addr_or_subfl mptcp_close_ssk(sk, ssk, subflow); spin_lock_bh(&msk->pm.lock);
- removed = true; + removed |= subflow->request_join; if (rm_type == MPTCP_MIB_RMSUBFLOW) __MPTCP_INC_STATS(sock_net(sk), rm_type); } @@ -843,7 +843,11 @@ static void mptcp_pm_nl_rm_addr_or_subfl if (!mptcp_pm_is_kernel(msk)) continue;
- if (rm_type == MPTCP_MIB_RMADDR) { + if (rm_type == MPTCP_MIB_RMADDR && rm_id && + !WARN_ON_ONCE(msk->pm.add_addr_accepted == 0)) { + /* Note: if the subflow has been closed before, this + * add_addr_accepted counter will not be decremented. + */ msk->pm.add_addr_accepted--; WRITE_ONCE(msk->pm.accept_addr, true); }