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| author | Tao Cui <cuitao@kylinos.cn> | 2026-06-16 12:18:46 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-07-04 13:41:32 +0200 |
| commit | 42da6ee329613c253f8bc7c74aba6338bd7ca6c7 (patch) | |
| tree | aa992515e30c97d4dd4c9c2c191d3f5a5fd76860 | |
| parent | a1f18ce9b26e2bcabed8d78772e724f907090988 (diff) | |
| download | linux-42da6ee329613c253f8bc7c74aba6338bd7ca6c7.tar.gz linux-42da6ee329613c253f8bc7c74aba6338bd7ca6c7.zip | |
mptcp: pm: fix extra_subflows underflow on userspace PM subflow creation
[ Upstream commit 14e9fea30b68fc75b2b3d97396a7e6adb544bd2a ]
The userspace PM increments extra_subflows after __mptcp_subflow_connect()
succeeds, but __mptcp_subflow_connect() calls mptcp_pm_close_subflow()
on failure to roll back the pre-increment done by the kernel PM's fill_*()
helpers. Because the userspace PM hasn't incremented yet at that point,
this decrement is spurious and causes extra_subflows to underflow.
Fix it by aligning the userspace PM with the kernel PM: increment
extra_subflows before calling __mptcp_subflow_connect(), so the existing
error path in subflow.c correctly rolls it back on failure. Also simplify
the error handling by taking pm.lock only when needed for cleanup.
Fixes: 77e4b94a3de6 ("mptcp: update userspace pm infos")
Cc: stable@vger.kernel.org
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-5-856831229976@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/mptcp/pm_userspace.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c index 9016f8900c19..5260a34a617e 100644 --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -410,18 +410,21 @@ int mptcp_nl_cmd_sf_create(struct sk_buff *skb, struct genl_info *info) goto create_err; } + spin_lock_bh(&msk->pm.lock); + msk->pm.subflows++; + spin_unlock_bh(&msk->pm.lock); + lock_sock(sk); err = __mptcp_subflow_connect(sk, &addr_l, &addr_r); release_sock(sk); - spin_lock_bh(&msk->pm.lock); - if (err) + if (err) { + spin_lock_bh(&msk->pm.lock); mptcp_userspace_pm_delete_local_addr(msk, &local); - else - msk->pm.subflows++; - spin_unlock_bh(&msk->pm.lock); + spin_unlock_bh(&msk->pm.lock); + } create_err: sock_put((struct sock *)msk); |