---
id: CVE-2026-90342
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Fix mmap_lock deadlock on arena lock failure

  Reported by the Sashiko AI review.

  arena_vm_fault() returns VM_FAULT_RETRY when it can't take
  arena->spinlock, but i…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Fix mmap_lock deadlock on arena lock failure

  Reported by the Sashiko AI review.

  arena_vm_fault() returns VM_FAULT_RETRY when it can't take
  arena->spinlock, but i…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b8467290edab4bafae352bf3f317055669a1a458 <
    af8087f16714f7620c4db3e732baaa1b2337948f
  - >-
    Linux >= b8467290edab4bafae352bf3f317055669a1a458 <
    0b10b945479c954393d62ee3229d2f224a4ca91c
  - Linux 7.0
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:32.877'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90342'
references:
  - url: 'https://git.kernel.org/stable/c/0b10b945479c954393d62ee3229d2f224a4ca91c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/af8087f16714f7620c4db3e732baaa1b2337948f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.817Z'
epss: 0.00198
epssPercentile: 0.08445
---

## Overview

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

bpf: Fix mmap_lock deadlock on arena lock failure

Reported by the Sashiko AI review.

arena_vm_fault() returns VM_FAULT_RETRY when it can't take
arena->spinlock, but it never took mmap_lock. The fault path assumes a
VM_FAULT_RETRY handler already dropped mmap_lock and re-takes it on the
retry, so mmap_lock gets taken twice and can deadlock:

	do_user_addr_fault()
	{
		fault = handle_mm_fault(...);   // calls arena_vm_fault()
		if (fault & VM_FAULT_RETRY)
			goto retry;   // re-locks mmap_lock
		mmap_read_unlock(mm);
	}

Return VM_FAULT_SIGBUS instead, for two reasons:

1. We could keep VM_FAULT_RETRY, but then we'd have to drop the fault
   lock first and cap the retry ourselves, the way __folio_lock_or_retry()
   does.

2. A failed raw_res_spin_lock_irqsave() already means a possible deadlock
   was detected, so retrying just hits the same lock again.

So returning VM_FAULT_RETRY here is overkill.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.