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| author | Tao Cui <cuitao@kylinos.cn> | 2026-06-02 22:14:12 +1000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-06-03 19:04:26 -0700 |
| commit | 14e9fea30b68fc75b2b3d97396a7e6adb544bd2a (patch) | |
| tree | 91a01a8dfe7cc58ba824527c3ac42704f4bfa186 /net | |
| parent | da23be77e1292cd611e736c3aa17da633d7ddce7 (diff) | |
| download | linux-next-14e9fea30b68fc75b2b3d97396a7e6adb544bd2a.tar.gz linux-next-14e9fea30b68fc75b2b3d97396a7e6adb544bd2a.zip | |
mptcp: pm: fix extra_subflows underflow on userspace PM subflow creation
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/mptcp/pm_userspace.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c index 8cbc1920afb4..0d3a95e676f1 100644 --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -408,19 +408,21 @@ int mptcp_pm_nl_subflow_create_doit(struct sk_buff *skb, struct genl_info *info) local.flags = entry.flags; local.ifindex = entry.ifindex; + spin_lock_bh(&msk->pm.lock); + msk->pm.extra_subflows++; + spin_unlock_bh(&msk->pm.lock); + lock_sock(sk); err = __mptcp_subflow_connect(sk, &local, &addr_r); release_sock(sk); - if (err) + if (err) { GENL_SET_ERR_MSG_FMT(info, "connect error: %d", err); - spin_lock_bh(&msk->pm.lock); - if (err) + spin_lock_bh(&msk->pm.lock); mptcp_userspace_pm_delete_local_addr(msk, &entry); - else - msk->pm.extra_subflows++; - spin_unlock_bh(&msk->pm.lock); + spin_unlock_bh(&msk->pm.lock); + } create_err: sock_put(sk); |