CVE-2025-21820— tty: xilinx_uartps: split sysrq handling
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I. Basic Information for CVE-2025-21820
Vulnerability Information
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Vulnerability Title
tty: xilinx_uartps: split sysrq handling
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于cdns_uart_console_write函数中未正确处理sysrq，可能导致死锁。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2025-21820
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Same Patch Batch · Linux · 2025-02-27 · 177 CVEs total
| CVE-2025-21756 | 7.8 HIGH | vsock: Keep the binding until socket destruction |
| CVE-2025-21770 | iommu: Fix potential memory leak in iopf_queue_remove_device() | |
| CVE-2025-21761 | openvswitch: use RCU protection in ovs_vport_cmd_fill_info() | |
| CVE-2025-21763 | neighbour: use RCU protection in __neigh_notify() | |
| CVE-2025-21762 | arp: use RCU protection in arp_xmit() | |
| CVE-2025-21764 | ndisc: use RCU protection in ndisc_alloc_skb() | |
| CVE-2025-21765 | ipv6: use RCU protection in ip6_default_advmss() | |
| CVE-2025-21766 | ipv4: use RCU protection in __ip_rt_update_pmtu() | |
| CVE-2025-21767 | clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context | |
| CVE-2025-21769 | ptp: vmclock: Add .owner to vmclock_miscdev_fops | |
| CVE-2025-21768 | net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels | |
| CVE-2025-21771 | sched_ext: Fix incorrect autogroup migration detection | |
| CVE-2025-21776 | USB: hub: Ignore non-compliant devices with too many configs or interfaces | |
| CVE-2025-21781 | batman-adv: fix panic during interface removal | |
| CVE-2025-21780 | drm/amdgpu: avoid buffer overflow attach in smu_sys_set_pp_table() | |
| CVE-2025-21779 | KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel | |
| CVE-2025-21778 | tracing: Do not allow mmap() of persistent ring buffer | |
| CVE-2025-21777 | ring-buffer: Validate the persistent meta data subbuf array | |
| CVE-2025-21775 | can: ctucanfd: handle skb allocation failure | |
| CVE-2025-21773 | can: etas_es58x: fix potential NULL pointer dereference on udev->serial |
Showing top 20 of 177 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
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Same vendor: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
V. Comments for CVE-2025-21820
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