Use After Free Affecting kernel-modules-extra package, versions <0:4.18.0-372.129.1.el8_6


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELMODULESEXTRA-8370152
  • published13 Nov 2024
  • disclosed27 Sept 2024

Introduced: 27 Sep 2024

CVE-2024-46858  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade RHEL:8 kernel-modules-extra to version 0:4.18.0-372.129.1.el8_6 or higher.
This issue was patched in RHSA-2024:9500.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-modules-extra package and not the kernel-modules-extra package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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.

CVSS Scores

version 3.1