CVE - CVE-2025-21820

CVE-ID
CVE-2025-21820	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3 URL:https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3 MISC:https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c URL:https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c MISC:https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2 URL:https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2 MISC:https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe URL:https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe MISC:https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065 URL:https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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