CVE-2022-49300

Summary

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

nbd: fix race between nbd_alloc_config() and module removal

When nbd module is being removing, nbd_alloc_config() may be called concurrently by nbd_genl_connect(), although try_module_get() will return false, but nbd_alloc_config() doesn't handle it.

The race may lead to the leak of nbd_config and its related resources (e.g, recv_workq) and oops in nbd_read_stat() due to the unload of nbd module as shown below:

BUG: kernel NULL pointer dereference, address: 0000000000000040 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Workqueue: knbd16-recv recv_work [nbd] RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd] Call Trace: recv_work+0x3b/0xb0 [nbd] process_one_work+0x1ed/0x390 worker_thread+0x4a/0x3d0 kthread+0x12a/0x150 ret_from_fork+0x22/0x30

Fixing it by checking the return value of try_module_get() in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV), assign nbd->config only when nbd_alloc_config() succeeds to ensure the value of nbd->config is binary (valid or NULL).

Also adding a debug message to check the reference counter of nbd_config during module removal.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 165cf2e0019fa6cedc75b456490c41494c34abb4affected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 2573f2375b64280be977431701ed5d33b75b9ad0affected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 8a7da4ced236ce6637fe70f14ca18e718d4bf9e9affected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 122e4adaff2439f1cc18cc7e931980fa7560df5caffected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 71c142f910da44421213ade601bcbd23ceae19faaffected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < 2888fa41985f93ed0a6837cfbb06bcbfd7fa2314affected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < d09525720dd5201756f698bee1076de9aefd4602affected
LinuxLinux5ea8d10802ec4c153a6e21eebaf412e2abd29736 < c55b2b983b0fa012942c3eb16384b2b722caa810affected
LinuxLinux4.12affected
LinuxLinux0 < 4.12unaffected
LinuxLinux4.14.283 <= 4.14.*unaffected
LinuxLinux4.19.247 <= 4.19.*unaffected
LinuxLinux5.4.198 <= 5.4.*unaffected
LinuxLinux5.10.122 <= 5.10.*unaffected
LinuxLinux5.15.47 <= 5.15.*unaffected
LinuxLinux5.17.15 <= 5.17.*unaffected
LinuxLinux5.18.4 <= 5.18.*unaffected
LinuxLinux5.19 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References