CVE-2025-38150

In the Linux kernel, the following vulnerability has been resolved:

af_packet: move notifiers packet_dev_mc out of rcu critical section

Syzkaller reports the following issue:

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:578 __mutex_lock+0x106/0xe80 kernel/locking/mutex.c:746 team_change_rx_flags+0x38/0x220 drivers/net/team/team_core.c:1781 dev_change_rx_flags net/core/dev.c:9145 [inline] __dev_set_promiscuity+0x3f8/0x590 net/core/dev.c:9189 netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9201 dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:286 packet_dev_mc net/packet/af_packet.c:3698 [inline] packet_dev_mclist_delete net/packet/af_packet.c:3722 [inline] packet_notifier+0x292/0xa60 net/packet/af_packet.c:4247 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline] call_netdevice_notifiers net/core/dev.c:2228 [inline] unregister_netdevice_many_notify+0x15d8/0x2330 net/core/dev.c:11972 rtnl_delete_link net/core/rtnetlink.c:3522 [inline] rtnl_dellink+0x488/0x710 net/core/rtnetlink.c:3564 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6955 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534

Calling PACKET_ADD_MEMBERSHIP on an ops-locked device can trigger the NETDEV_UNREGISTER notifier, which may require disabling promiscuous and/or allmulti mode. Both of these operations require acquiring the netdev instance lock.

Move the call to packet_dev_mc outside of the RCU critical section. The mclist modifications (add, del, flush, unregister) are protected by the RTNL, not the RCU. The RCU only protects the sklist and its associated sks. The delayed operation on the mclist entry remains within the RTNL.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/2dd4781c5af99415ebbd2f7cc763feb109863c05
• https://git.kernel.org/stable/c/d8d85ef0a631df9127f202e6371bb33a0b589952