CVE-2024-26999

A flaw was found in the Linux kernel's pmac_zilog serial driver. A local attacker can cause a Denial of Service (DoS) and crash the system when the driver is configured as an active serial console. During heavy serial traffic, an error-handling routine attempts to acquire a lock that is already held by the system. This recursive locking results in a fatal kernel panic or stops incoming serial communication.

A flaw was found in the Linux kernel's pmac_zilog serial driver, rated as having Moderate impact for Red Hat Enterprise Linux 8 and 9 (kernel and kernel-rt), with a CVSS 3.1 base score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), matching the NIST score. When the pmac_zilog driver is configured as an active serial console, a local attacker can generate heavy serial traffic that triggers a receive-interrupt (rx irq) flood. The error-handling path in the driver then attempts to acquire a spinlock that is already held by the interrupt handler, causing recursive spinlock acquisition that results in a fatal kernel BUG/panic (for example when CONFIG_DEBUG_SPINLOCK is enabled) or stops incoming serial communication, both of which are a local denial of service. In Red Hat Enterprise Linux 8 and 9, the affected pmac_zilog source is not built in the shipped kernel packages, as found by Red Hat's automated build check, and the affected records were delegated to the kernel maintainers with a WONTFIX outcome; the residual risk to Red Hat customers is therefore limited to configurations that build and use this driver as an active serial console. The RHEL 6 and RHEL 7 ELS streams are out of support, Fedora received a fix through its community kernel updates, and the Hosted OpenShift (OSD and ARO) affected records are delegated to the kernel with their trackers closed without a fix.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.