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TI-2021-21856 Aliases CVE-2021-47195GHSA-q34q-mrch-vm2x

spi: fix use-after-free of the add_lock mutex

Priority LOW 24CWE-416Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.

Summary

In the Linux kernel, the following vulnerability has been resolved: spi: fix use-after-free of the add_lock mutex Commit 6098475d4cb4 ("spi: Fix deadlock when adding SPI controllers on SPI buses") introduced a per-controller mutex. But mutex_unlock() of said lock is called after the controller is already freed: spi_unregister_controller(ctlr) -> put_device(&ctlr->dev) -> spi_controller_release(dev) -> mutex_unlock(&ctrl->add_lock) Move the put_device() after the mutex_unlock().

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00219 12th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.15, 5.15.5, 5.16Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux5.14.15 to before 5.155.15Patch availableCNA
LinuxLinux5.15 and later5.15.5, 5.16Patch availableCNA
  • Linux VendorLinux Affected 5.14.15 to before 5.15 Fixed in 5.15 Patch available CNA
  • Linux VendorLinux Affected 5.15 and later Fixed in 5.15.5, 5.16 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*after 5.15.0, before 5.15.5VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions after 5.15.0, before 5.15.5 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.15
  • Fix · CNA Linux (Linux) Fixed in 5.15.5, 5.16

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Not affected: 3 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-47195
  2. 2026-10-03 Alias added: GHSA-q34q-mrch-vm2x

References

Patch 2

Other 2

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences