The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 9366922adc6a71378ca01f898c41be295309f044 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024083011-antics-rented-acb7@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

9366922adc6a ("mptcp: pm: fix ID 0 endp usage after multiple re-creations") 8b8ed1b429f8 ("mptcp: pm: reuse ID 0 after delete and re-add") 48e50dcbcbaa ("mptcp: pm: avoid possible UaF when selecting endp") 85df533a787b ("mptcp: pm: do not ignore 'subflow' if 'signal' flag is also set") cd7c957f936f ("mptcp: pm: don't try to create sf if alloc failed") c95eb32ced82 ("mptcp: pm: reduce indentation blocks") 40eec1795cc2 ("mptcp: pm: update add_addr counters after connect") 6a09788c1a66 ("mptcp: pm: inc RmAddr MIB counter once per RM_ADDR ID") e571fb09c893 ("selftests: mptcp: add speed env var") 4aadde088a58 ("selftests: mptcp: add fullmesh env var") 080b7f5733fd ("selftests: mptcp: add fastclose env var") 662aa22d7dcd ("selftests: mptcp: set all env vars as local ones") 9e9d176df8e9 ("selftests: mptcp: add pm_nl_set_endpoint helper") 1534f87ee0dc ("selftests: mptcp: drop sflags parameter") 595ef566a2ef ("selftests: mptcp: drop addr_nr_ns1/2 parameters") 0c93af1f8907 ("selftests: mptcp: drop test_linkfail parameter") be7e9786c915 ("selftests: mptcp: set FAILING_LINKS in run_tests") 4369c198e599 ("selftests: mptcp: test userspace pm out of transfer") 528cb5f2a1e8 ("mptcp: pass addr to mptcp_pm_alloc_anno_list") ae947bb2c253 ("selftests: mptcp: join: skip Fastclose tests if not supported")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9366922adc6a71378ca01f898c41be295309f044 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" matttbe@kernel.org Date: Wed, 28 Aug 2024 08:14:33 +0200 Subject: [PATCH] mptcp: pm: fix ID 0 endp usage after multiple re-creations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

'local_addr_used' and 'add_addr_accepted' are decremented for addresses not related to the initial subflow (ID0), because the source and destination addresses of the initial subflows are known from the beginning: they don't count as "additional local address being used" or "ADD_ADDR being accepted".

It is then required not to increment them when the entrypoint used by the initial subflow is removed and re-added during a connection. Without this modification, this entrypoint cannot be removed and re-added more than once.

Reported-by: Arınç ÜNAL arinc.unal@arinc9.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/512 Fixes: 3ad14f54bd74 ("mptcp: more accurate MPC endpoint tracking") Reported-by: syzbot+455d38ecd5f655fc45cf@syzkaller.appspotmail.com Closes: https://lore.kernel.org/00000000000049861306209237f4@google.com Cc: stable@vger.kernel.org Tested-by: Arınç ÜNAL arinc.unal@arinc9.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 3ff273e219f2..a93450ded50a 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -615,12 +615,13 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)

fullmesh = !!(local.flags & MPTCP_PM_ADDR_FLAG_FULLMESH);

- msk->pm.local_addr_used++; __clear_bit(local.addr.id, msk->pm.id_avail_bitmap);

/* Special case for ID0: set the correct ID */ if (local.addr.id == msk->mpc_endpoint_id) local.addr.id = 0; + else /* local_addr_used is not decr for ID 0 */ + msk->pm.local_addr_used++;

nr = fill_remote_addresses_vec(msk, &local.addr, fullmesh, addrs); if (nr == 0) @@ -750,7 +751,9 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk) spin_lock_bh(&msk->pm.lock);

if (sf_created) { - msk->pm.add_addr_accepted++; + /* add_addr_accepted is not decr for ID 0 */ + if (remote.id) + msk->pm.add_addr_accepted++; if (msk->pm.add_addr_accepted >= add_addr_accept_max || msk->pm.subflows >= subflows_max) WRITE_ONCE(msk->pm.accept_addr, false);