CVE-2025-21820 (GCVE-0-2025-21820)

Vulnerability from cvelistv5 – Published: 2025-02-27 20:04 – Updated: 2026-05-11 21:07
VLAI
Title
tty: xilinx_uartps: split sysrq handling
Summary
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.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < e22a97700901ba5e8bf8db68056a0d50f9440cae (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < de5bd24197bd9ee37ec1e379a3d882bbd15c5065 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 9b88a7c4584ba67267a051069b8abe44fc9595b2 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 4410dba9807a17a93f649a9f5870ceaf30a675a3 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < b06f388994500297bb91be60ffaf6825ecfd2afe (git)
Create a notification for this product.
Linux Linux Affected: 4.6
Unaffected: 0 , < 4.6 (semver)
Unaffected: 5.15.179 , ≤ 5.15.* (semver)
Unaffected: 6.1.129 , ≤ 6.1.* (semver)
Unaffected: 6.6.78 , ≤ 6.6.* (semver)
Unaffected: 6.12.14 , ≤ 6.12.* (semver)
Unaffected: 6.13.3 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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      "cve": "CVE-2025-21820",
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      "source": "Red Hat CSAF VEX",
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      "title": "kernel: tty: xilinx_uartps: split sysrq handling",
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}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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