Riskcovery

CVE-2025-21820

tty: xilinx_uartps: split sysrq handling

State
Published
Severity
Not scored
Published
Feb 27, 2025
Updated
May 11, 2026
Reserved
Dec 29, 2024

Read the record on cve.org

Description

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

tty: xilinx_uartps: split sysrq handling

lockdep detects the following circular locking dependency:

CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock()

The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock.

Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before e22a97700901ba5e8bf8db68056a0d50f9440caeAffected
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before de5bd24197bd9ee37ec1e379a3d882bbd15c5065Affected
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before 8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801cAffected
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before 9b88a7c4584ba67267a051069b8abe44fc9595b2Affected
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before 4410dba9807a17a93f649a9f5870ceaf30a675a3Affected
  • 74ea66d4ca061a3cd4c0e924e51b60e924644852 to before b06f388994500297bb91be60ffaf6825ecfd2afeAffected
LinuxLinux
  • 4.6Affected
  • before 4.6Not affected
  • 5.15.179 through 5.15.*Not affected
  • 6.1.129 through 6.1.*Not affected
  • 6.6.78 through 6.6.*Not affected
  • 6.12.14 through 6.12.*Not affected
  • 6.13.3 through 6.13.*Not affected
  • 6.14 and laterNot affected

References

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