In the Linux kernel, the following vulnerability has been resolved:

irqchip/gic-v3: Do not enable irqs when handling spurious interrups

We triggered the following error while running our 4.19 kernel
with the pseudo-NMI patches backported to it:

[ 14.816231] ------------[ cut here ]------------
[ 14.816231] kernel BUG at irq.c:99!
[ 14.816232] Internal error: Oops - BUG: 0 [#1] SMP
[ 14.816232] Process swapper/0 (pid: 0, stack limit = 0x(____ptrval____))
[ 14.816233] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G O 4.19.95.aarch64 #14
[ 14.816233] Hardware name: evb (DT)
[ 14.816234] pstate: 80400085 (Nzcv daIf +PAN -UAO)
[ 14.816234] pc : asm_nmi_enter+0x94/0x98
[ 14.816235] lr : asm_nmi_enter+0x18/0x98
[ 14.816235] sp : ffff000008003c50
[ 14.816235] pmr_save: 00000070
[ 14.816237] x29: ffff000008003c50 x28: ffff0000095f56c0
[ 14.816238] x27: 0000000000000000 x26: ffff000008004000
[ 14.816239] x25: 00000000015e0000 x24: ffff8008fb916000
[ 14.816240] x23: 0000000020400005 x22: ffff0000080817cc
[ 14.816241] x21: ffff000008003da0 x20: 0000000000000060
[ 14.816242] x19: 00000000000003ff x18: ffffffffffffffff
[ 14.816243] x17: 0000000000000008 x16: 003d090000000000
[ 14.816244] x15: ffff0000095ea6c8 x14: ffff8008fff5ab40
[ 14.816244] x13: ffff8008fff58b9d x12: 0000000000000000
[ 14.816245] x11: ffff000008c8a200 x10: 000000008e31fca5
[ 14.816246] x9 : ffff000008c8a208 x8 : 000000000000000f
[ 14.816247] x7 : 0000000000000004 x6 : ffff8008fff58b9e
[ 14.816248] x5 : 0000000000000000 x4 : 0000000080000000
[ 14.816249] x3 : 0000000000000000 x2 : 0000000080000000
[ 14.816250] x1 : 0000000000120000 x0 : ffff0000095f56c0
[ 14.816251] Call trace:
[ 14.816251] asm_nmi_enter+0x94/0x98
[ 14.816251] el1_irq+0x8c/0x180 (IRQ C)
[ 14.816252] gic_handle_irq+0xbc/0x2e4
[ 14.816252] el1_irq+0xcc/0x180 (IRQ B)
[ 14.816253] arch_timer_handler_virt+0x38/0x58
[ 14.816253] handle_percpu_devid_irq+0x90/0x240
[ 14.816253] generic_handle_irq+0x34/0x50
[ 14.816254] __handle_domain_irq+0x68/0xc0
[ 14.816254] gic_handle_irq+0xf8/0x2e4
[ 14.816255] el1_irq+0xcc/0x180 (IRQ A)
[ 14.816255] arch_cpu_idle+0x34/0x1c8
[ 14.816255] default_idle_call+0x24/0x44
[ 14.816256] do_idle+0x1d0/0x2c8
[ 14.816256] cpu_startup_entry+0x28/0x30
[ 14.816256] rest_init+0xb8/0xc8
[ 14.816257] start_kernel+0x4c8/0x4f4
[ 14.816257] Code: 940587f1 d5384100 b9401001 36a7fd01 (d4210000)
[ 14.816258] Modules linked in: start_dp(O) smeth(O)
[ 15.103092] ---[ end trace 701753956cb14aa8 ]---
[ 15.103093] Kernel panic - not syncing: Fatal exception in interrupt
[ 15.103099] SMP: stopping secondary CPUs
[ 15.103100] Kernel Offset: disabled
[ 15.103100] CPU features: 0x36,a2400218
[ 15.103100] Memory Limit: none

which is cause by a 'BUG_ON(in_nmi())' in nmi_enter().

From the call trace, we can find three interrupts (noted A, B, C above):
interrupt (A) is preempted by (B), which is further interrupted by (C).

Subsequent investigations show that (B) results in nmi_enter() being
called, but that it actually is a spurious interrupt. Furthermore,
interrupts are reenabled in the context of (B), and (C) fires with
NMI priority. We end-up with a nested NMI situation, something
we definitely do not want to (and cannot) handle.

The bug here is that spurious interrupts should never result in any
state change, and we should just return to the interrupted context.
Moving the handling of spurious interrupts as early as possible in
the GICv3 handler fixes this issue.

[maz: rewrote commit message, corrected Fixes: tag]
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 11 Dec 2024 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 4.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Mon, 04 Nov 2024 12:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-04T07:01:14.501Z

Reserved: 2024-02-27T18:42:55.942Z

Link: CVE-2021-46961

cve-icon Vulnrichment

Updated: 2024-08-04T05:17:42.893Z

cve-icon NVD

Status : Modified

Published: 2024-02-27T19:04:06.907

Modified: 2025-04-22T16:15:20.500

Link: CVE-2021-46961

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-02-27T00:00:00Z

Links: CVE-2021-46961 - Bugzilla

cve-icon OpenCVE Enrichment

No data.