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Vulnerability · Published Feb 27, 2025 · Assigned by Linux

CVE-2025-21820tty: xilinx_uartps: split sysrq handling

Medium 5.5

In plain English

A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.2%top 94.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.129-1DEBIAN-CVE-2025-21820
Debian:13linux6.12.15-1DEBIAN-CVE-2025-21820
Debian:14linux6.12.15-1DEBIAN-CVE-2025-21820
Ubuntu:22.04:LTSlinux5.15.0-140.150UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux6.8.0-64.67UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-aws5.15.0-1084.91UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-aws6.8.0-1032.34UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1032.34~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure5.15.0-1089.98UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-azure6.8.0-1034.39UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-azure-6.116.11.0-1015.15~24.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1034.39~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1089.98.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-azure-nvidia6.8.0-1022.23UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gcp5.15.0-1083.92UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-gcp6.8.0-1033.35UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-gcp-6.116.11.0-1015.15~24.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1033.35~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gke5.15.0-1081.87UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-gke6.8.0-1028.32UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1066.74UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1015.17UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-hwe-6.116.11.0-26.26~24.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-64.67~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-ibm5.15.0-1076.79UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-ibm6.8.0-1029.29UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1029.29~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1079.85UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-kvm5.15.0-1080.85UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-140.150UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-64.67.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.116.11.0-1014.15~24.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-64.67.1~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1078.79UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1031.34UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-nvidia-6.116.11.0-1010.10UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1031.34~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1031.34.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1037.37UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1008.8UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1026.26UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-oem-6.116.11.0-1022.22UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-oem-6.86.8.0-1031.31UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oracle5.15.0-1081.87UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-oracle6.8.0-1029.30UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1029.30~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-raspi5.15.0-1078.81UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-raspi6.8.0-1031.35UBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-64.67~22.04.1UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-21820
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1017.18UBUNTU-CVE-2025-21820
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1050.54UBUNTU-CVE-2025-21820

Affected products (as reported)

VendorProductVersions
Linux Linux 74ea66d4ca061a3cd4c0e924e51b60e924644852 – before e22a97700901ba5e8bf8db68056a0d50f9440cae74ea66d4ca061a3cd4c0e924e51b60e924644852 – before de5bd24197bd9ee37ec1e379a3d882bbd15c506574ea66d4ca061a3cd4c0e924e51b60e924644852 – before 8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c74ea66d4ca061a3cd4c0e924e51b60e924644852 – before 9b88a7c4584ba67267a051069b8abe44fc9595b274ea66d4ca061a3cd4c0e924e51b60e924644852 – before 4410dba9807a17a93f649a9f5870ceaf30a675a374ea66d4ca061a3cd4c0e924e51b60e924644852 – before b06f388994500297bb91be60ffaf6825ecfd2afe
Linux Linux 4.6

References