CVE-2023-52993

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> x86/i8259: Mark legacy PIC interrupts with IRQ_LEVEL<br /> <br /> Baoquan reported that after triggering a crash the subsequent crash-kernel<br /> fails to boot about half of the time. It triggers a NULL pointer<br /> dereference in the periodic tick code.<br /> <br /> This happens because the legacy timer interrupt (IRQ0) is resent in<br /> software which happens in soft interrupt (tasklet) context. In this context<br /> get_irq_regs() returns NULL which leads to the NULL pointer dereference.<br /> <br /> The reason for the resend is a spurious APIC interrupt on the IRQ0 vector<br /> which is captured and leads to a resend when the legacy timer interrupt is<br /> enabled. This is wrong because the legacy PIC interrupts are level<br /> triggered and therefore should never be resent in software, but nothing<br /> ever sets the IRQ_LEVEL flag on those interrupts, so the core code does not<br /> know about their trigger type.<br /> <br /> Ensure that IRQ_LEVEL is set when the legacy PCI interrupts are set up.