CVE-2024-35934

Technical Description

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

net/smc: reduce rtnl pressure in smc_pnet_create_pnetids_list()

Many syzbot reports show extreme rtnl pressure, and many of them hint

that smc acquires rtnl in netns creation for no good reason [1]

This patch returns early from smc_pnet_net_init()

if there is no netdevice yet.

I am not even sure why smc_pnet_create_pnetids_list() even exists,

because smc_pnet_netdev_event() is also calling

smc_pnet_add_base_pnetid() when handling NETDEV_UP event.

[1] extract of typical syzbot reports

2 locks held by syz-executor.3/12252:

#0: ffffffff8f369610 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x4c7/0x7b0 net/core/net_namespace.c:491

#1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_create_pnetids_list net/smc/smc_pnet.c:809 [inline]

#1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_net_init+0x10a/0x1e0 net/smc/smc_pnet.c:878

2 locks held by syz-executor.4/12253:

#0: ffffffff8f369610 (perne

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References