CVE-2024-39296 bonding: fix oops during rmmod

2024-06-2514:22:40

Linux

www.cve.org

linux kernel

bonding

rmmod

oops fix

race condition

module removal

0.0004 Low

EPSS

Percentile

15.7%

JSON

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

bonding: fix oops during rmmod

“rmmod bonding” causes an oops ever since commit cc317ea3d927 (“bonding:
remove redundant NULL check in debugfs function”). Here are the relevant
functions being called:

bonding_exit()
bond_destroy_debugfs()
debugfs_remove_recursive(bonding_debug_root);
bonding_debug_root = NULL; <--------- SET TO NULL HERE
bond_netlink_fini()
rtnl_link_unregister()
__rtnl_link_unregister()
unregister_netdevice_many_notify()
bond_uninit()
bond_debug_unregister()
(commit removed check for bonding_debug_root == NULL)
debugfs_remove()
simple_recursive_removal()
down_write() -> OOPS

However, reverting the bad commit does not solve the problem completely
because the original code contains a race that could cause the same
oops, although it was much less likely to be triggered unintentionally:

CPU1
rmmod bonding
bonding_exit()
bond_destroy_debugfs()
debugfs_remove_recursive(bonding_debug_root);

CPU2
echo -bond0 > /sys/class/net/bonding_masters
bond_uninit()
bond_debug_unregister()
if (!bonding_debug_root)

CPU1
bonding_debug_root = NULL;

So do NOT revert the bad commit (since the removed checks were racy
anyway), and instead change the order of actions taken during module
removal. The same oops can also happen if there is an error during
module init, so apply the same fix there.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/net/bonding/bond_main.c"
    ],
    "versions": [
      {
        "version": "cc317ea3d927",
        "lessThan": "f07224c16678",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "cc317ea3d927",
        "lessThan": "cf48aee81103",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "cc317ea3d927",
        "lessThan": "a45835a0bb6e",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/net/bonding/bond_main.c"
    ],
    "versions": [
      {
        "version": "6.6",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.6",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.34",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.5",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10-rc1",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]