AZL-57749
See a problem?- Import Source
- https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-57749.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/AZL-57749
- Upstream
- Published
- 2025-02-27T20:16:04Z
- Modified
- 2026-04-01T05:19:12.277416Z
- Severity
-
- 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- CVE-2025-21820 affecting package kernel for versions less than 5.15.179.1-1
- Details
-
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 ========================== ============================ cdnsuartisr() printk() uartportlock(port) consolelock() cdnsuartconsolewrite() if (!port->sysrq) uartportlock(port) uarthandlebreak() port->sysrq = ... uarthandlesysrqchar() printk() consolelock()
The fixed commit attempts to avoid this situation by only taking the port lock in cdnsuartconsolewrite if port->sysrq unset. However, if (as shown above) cdnsuartconsolewrite 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