CVE-2021-46904

Summary

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

net: hso: fix null-ptr-deref during tty device unregistration

Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref.

The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number.

Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < a462067d7c8e6953a733bf5ade8db947b1bb5449affected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < 145c89c441d27696961752bf51b323f347601beeaffected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < caf5ac93b3b5d5fac032fc11fbea680e115421b4affected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < 92028d7a31e55d53e41cff679156b9432cffcb36affected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < 4a2933c88399c0ebc738db39bbce3ae89786d723affected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72acaffected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < 388d05f70f1ee0cac4a2068fd295072f1a44152aaffected
LinuxLinux72dc1c096c7051a48ab1dbb12f71976656b55eb5 < 8a12f8836145ffe37e9c8733dce18c22fb668b66affected
LinuxLinux2.6.27affected
LinuxLinux0 < 2.6.27unaffected
LinuxLinux4.4.268 <= 4.4.*unaffected
LinuxLinux4.9.268 <= 4.9.*unaffected
LinuxLinux4.14.232 <= 4.14.*unaffected
LinuxLinux4.19.187 <= 4.19.*unaffected
LinuxLinux5.4.112 <= 5.4.*unaffected
LinuxLinux5.10.30 <= 5.10.*unaffected
LinuxLinux5.11.14 <= 5.11.*unaffected
LinuxLinux5.12 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

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

CVE Program Container

Additional References

References