CVE-2023-52993: linux kernel Null Dereference — Fix

Description

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

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.18 — 4.14.305
linux	linux_kernel	4.15 — 4.19.272
linux	linux_kernel	4.20 — 5.4.231
linux	linux_kernel	5.5 — 5.10.166
linux	linux_kernel	5.11 — 5.15.91
linux	linux_kernel	5.16 — 6.1.9
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0b08201158f177aab469e356b4d6af24fdd118df https://git.kernel.org/stable/c/137f1b47da5f58805da42c1b7811e28c1e353f39 https://git.kernel.org/stable/c/496975d1a2937f4baadf3d985991b13fc4fc4f27 https://git.kernel.org/stable/c/5fa55950729d0762a787451dc52862c3f850f859 https://git.kernel.org/stable/c/744fe9be9665227335539b7a77ece8d9ff62b6c0 https://git.kernel.org/stable/c/8770cd9d7c14aa99c255a0d08186f0be953e1638 https://git.kernel.org/stable/c/e284c273dbb4c1ed68d4204bff94d0b10e4a90f5

Frequently Asked Questions

What is CVE-2023-52993? +

In the Linux kernel, the following vulnerability has been resolved: x86/i8259: Mark legacy PIC interrupts with IRQ_LEVEL Baoquan reported that after triggering a crash the subsequent crash-kernel fails to boot about half of the time. It triggers a NULL pointer dereference in the periodic tick code. This happens because the legacy timer interrupt (IRQ0) is resent in software which happens in soft interrupt (tasklet) context. In this context get_irq_regs() returns NULL which leads to the NULL pointer dereference. The reason for the resend is a spurious APIC interrupt on the IRQ0 vector which is captured and leads to a resend when the legacy timer interrupt is enabled. This is wrong because the legacy PIC interrupts are level triggered and therefore should never be resent in software, but nothing ever sets the IRQ_LEVEL flag on those interrupts, so the core code does not know about their trigger type. Ensure that IRQ_LEVEL is set when the legacy PCI interrupts are set up. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2023-52993? +

CVE-2023-52993 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2023-52993? +

CVE-2023-52993 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-52993? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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