CVE-2024-26998

Summary

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

serial: core: Clearing the circular buffer before NULLifying it

The circular buffer is NULLified in uart_tty_port_shutdown() under the spin lock. However, the PM or other timer based callbacks may still trigger after this event without knowning that buffer pointer is not valid. Since the serial code is a bit inconsistent in checking the buffer state (some rely on the head-tail positions, some on the buffer pointer), it's better to have both aligned, i.e. buffer pointer to be NULL and head-tail possitions to be the same, meaning it's empty. This will prevent asynchronous calls to dereference NULL pointer as reported recently in 8250 case:

BUG: kernel NULL pointer dereference, address: 00000cf5 Workqueue: pm pm_runtime_work EIP: serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) … ? serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) __start_tx (drivers/tty/serial/8250/8250_port.c:1551) serial8250_start_tx (drivers/tty/serial/8250/8250_port.c:1654) serial_port_runtime_suspend (include/linux/serial_core.h:667 drivers/tty/serial/serial_port.c:63) __rpm_callback (drivers/base/power/runtime.c:393) ? serial_port_remove (drivers/tty/serial/serial_port.c:50) rpm_suspend (drivers/base/power/runtime.c:447)

The proposed change will prevent ->start_tx() to be called during suspend on shut down port.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux434beb66368d4fb4d3119c2116b9398500adbf47 < 7ae7104d54342433a3a73975f6569beefdd86350affected
LinuxLinux43066e32227ecde674e8ae1fcdd4a1ede67680c2 < bb1118905e875c111d7ccef9aee86ac5e4e7f985affected
LinuxLinux43066e32227ecde674e8ae1fcdd4a1ede67680c2 < 9cf7ea2eeb745213dc2a04103e426b960e807940affected
LinuxLinuxa629a9b2f7699314a4abe8fbc37b0ee667b60f33affected
LinuxLinux6.6.24 < 6.6.29affected
LinuxLinux6.7.12 < 6.8affected
LinuxLinux6.8affected
LinuxLinux0 < 6.8unaffected
LinuxLinux6.6.29 <= 6.6.*unaffected
LinuxLinux6.8.8 <= 6.8.*unaffected
LinuxLinux6.9 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

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

CVE Program Container

Additional References

References