mptcp: pm: fix data race in add_addr timer callback

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[ Upstream commit a7aad5b69d ]

The timer callback reads entry->retrans_times outside pm.lock to decide
whether to call mptcp_pm_subflow_established(). Since
mptcp_pm_announced_del_timer() can concurrently set retrans_times =
ADD_ADDR_RETRANS_MAX under pm.lock, a race condition exists.

I discovered this issue while studying the code. AI tools helped me to
verify the issue can potentially happen under race conditions.

Use a local 'retransmit' flag set inside pm.lock to capture whether
retransmission is still possible when the lock is taken. This allows to
call mptcp_pm_subflow_established() accordingly, and not depending on
the situation that can be different when checked outside the pm.lock.

Fixes: 348d5c1dec ("mptcp: move to next addr when timeout")
Cc: stable@vger.kernel.org
Signed-off-by: Qing Luo <luoqing@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260803-net-mptcp-misc-fixes-7-2-rc6-v2-4-b8f496d71664@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ applied hunk to mptcp_pm_add_timer() in net/mptcp/pm_netlink.c instead of pm.c, dropping the absent adaptive-timeout shift line ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Qing Luo 2026-08-25 07:24:31 -04:00 • committed by Greg Kroah-Hartman

parent 1f26487e83

commit efbb6baa96

1 changed files with 4 additions and 2 deletions

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net/mptcp/pm_netlink.c

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