From: "Matthieu Baerts (NGI0)" matttbe@kernel.org

mainline inclusion from mainline-v6.11-rc5 commit 48e50dcbcbaaf713d82bf2da5c16aeced94ad07d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAOY17 CVE: CVE-2024-44974

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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select_local_address() and select_signal_address() both select an endpoint entry from the list inside an RCU protected section, but return a reference to it, to be read later on. If the entry is dereferenced after the RCU unlock, reading info could cause a Use-after-Free.

A simple solution is to copy the required info while inside the RCU protected section to avoid any risk of UaF later. The address ID might need to be modified later to handle the ID0 case later, so a copy seems OK to deal with.

Reported-by: Paolo Abeni pabeni@redhat.com Closes: https://lore.kernel.org/45cd30d3-7710-491c-ae4d-a1368c00beb1@redhat.com Fixes: 01cacb00b35c ("mptcp: add netlink-based PM") 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-v1-14-38035d40de5b... Signed-off-by: Jakub Kicinski kuba@kernel.org

Conflicts: net/mptcp/pm_netlink.c [Did not backport 90d930882139 ("mptcp: constify a bunch of of helpers"), 85df533a787b ("mptcp: pm: do not ignore 'subflow' if 'signal' flag is also set"), 86e39e04482b ("mptcp: keep track of local endpoint still available for each msk").] Signed-off-by: Liu Jian liujian56@huawei.com --- net/mptcp/pm_netlink.c | 44 ++++++++++++++++++++++++------------------ 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 0d6f3d912891..824420c4e8f9 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -128,11 +128,13 @@ static bool lookup_subflow_by_saddr(const struct list_head *list, return false; }

-static struct mptcp_pm_addr_entry * +static bool select_local_address(const struct pm_nl_pernet *pernet, - struct mptcp_sock *msk) + struct mptcp_sock *msk, + struct mptcp_pm_addr_entry *new_entry) { - struct mptcp_pm_addr_entry *entry, *ret = NULL; + struct mptcp_pm_addr_entry *entry; + bool found = false;

rcu_read_lock(); spin_lock_bh(&msk->join_list_lock); @@ -146,19 +148,23 @@ select_local_address(const struct pm_nl_pernet *pernet, if (entry->addr.family == ((struct sock *)msk)->sk_family && !lookup_subflow_by_saddr(&msk->conn_list, &entry->addr) && !lookup_subflow_by_saddr(&msk->join_list, &entry->addr)) { - ret = entry; + *new_entry = *entry; + found = true; break; } } spin_unlock_bh(&msk->join_list_lock); rcu_read_unlock(); - return ret; + + return found; }

-static struct mptcp_pm_addr_entry * -select_signal_address(struct pm_nl_pernet *pernet, unsigned int pos) +static bool +select_signal_address(struct pm_nl_pernet *pernet, unsigned int pos, + struct mptcp_pm_addr_entry *new_entry) { - struct mptcp_pm_addr_entry *entry, *ret = NULL; + struct mptcp_pm_addr_entry *entry; + bool found = false; int i = 0;

rcu_read_lock(); @@ -171,12 +177,14 @@ select_signal_address(struct pm_nl_pernet *pernet, unsigned int pos) if (!(entry->addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL)) continue; if (i++ == pos) { - ret = entry; + *new_entry = *entry; + found = true; break; } } rcu_read_unlock(); - return ret; + + return found; }

static void check_work_pending(struct mptcp_sock *msk) @@ -306,7 +314,7 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) { struct mptcp_addr_info remote = { 0 }; struct sock *sk = (struct sock *)msk; - struct mptcp_pm_addr_entry *local; + struct mptcp_pm_addr_entry local; struct pm_nl_pernet *pernet;

pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id); @@ -318,13 +326,12 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)

/* check first for announce */ if (msk->pm.add_addr_signaled < msk->pm.add_addr_signal_max) { - local = select_signal_address(pernet, - msk->pm.add_addr_signaled);

- if (local) { - if (mptcp_pm_alloc_anno_list(msk, local)) { + if (select_signal_address(pernet, + msk->pm.add_addr_signaled, &local)) { + if (mptcp_pm_alloc_anno_list(msk, &local)) { msk->pm.add_addr_signaled++; - mptcp_pm_announce_addr(msk, &local->addr, false); + mptcp_pm_announce_addr(msk, &local.addr, false); } } else { /* pick failed, avoid fourther attempts later */ @@ -339,13 +346,12 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) msk->pm.subflows < msk->pm.subflows_max) { remote_address((struct sock_common *)sk, &remote);

- local = select_local_address(pernet, msk); - if (local) { + if (select_local_address(pernet, msk, &local)) { msk->pm.local_addr_used++; msk->pm.subflows++; check_work_pending(msk); spin_unlock_bh(&msk->pm.lock); - __mptcp_subflow_connect(sk, &local->addr, &remote); + __mptcp_subflow_connect(sk, &local.addr, &remote); spin_lock_bh(&msk->pm.lock); return; }