CVE-2024-46858 mptcp: pm: Fix uaf in __timer_delete_sync
A race condition in the Linux kernel MPTCP path manager allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-46858?
CVE-2024-46858 is a high-severity use after free vulnerability in Linux kernel, published on 27 Sep 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mptcp: pm: Fix uaf in __timer_delete_sync
There are two paths to access mptcp_pm_del_add_timer, result in a race condition:
CPU1 CPU2 ==== ==== net_rx_action napi_poll netlink_sendmsg __napi_poll netlink_unicast process_backlog netlink_unicast_kernel __netif_receive_skb genl_rcv __netif_receive_skb_one_core netlink_rcv_skb NF_HOOK genl_rcv_msg ip_local_deliver_finish genl_family_rcv_msg ip_protocol_deliver_rcu genl_family_rcv_msg_doit tcp_v4_rcv mptcp_pm_nl_flush_addrs_doit tcp_v4_do_rcv mptcp_nl_remove_addrs_list tcp_rcv_established mptcp_pm_remove_addrs_and_subflows tcp_data_queue remove_anno_list_by_saddr mptcp_incoming_options mptcp_pm_del_add_timer mptcp_pm_del_add_timer kfree(entry)
In remove_anno_list_by_saddr(running on CPU2), after leaving the critical zone protected by "pm.lock", the entry will be released, which leads to the occurrence of uaf in the mptcp_pm_del_add_timer(running on CPU1).
Keeping a reference to add_timer inside the lock, and calling sk_stop_timer_sync() with this reference, instead of "entry->add_timer".
Move list_del(&entry->list) to mptcp_pm_del_add_timer and inside the pm lock, do not directly access any members of the entry outside the pm lock, which can avoid similar "entry->x" uaf.
Weakness: CWE-416
Which versions are affected by CVE-2024-46858?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-46858?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2024-46858 being exploited?
There is no known exploitation of CVE-2024-46858 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-49785, BELL-CVE-2024-46858, DEBIAN-CVE-2024-46858, GHSA-4mm4-rvx3-h58h, UBUNTU-CVE-2024-46858.