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TI-2021-22204 Aliases CVE-2021-47556

ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce()

Priority LOW 24CWE-476Published · 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: 9 fixed, 2 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-476.

Summary

In the Linux kernel, the following vulnerability has been resolved: ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce() ethtool_set_coalesce() now uses both the .get_coalesce() and .set_coalesce() callbacks. But the check for their availability is buggy, so changing the coalesce settings on a device where the driver provides only _one_ of the callbacks results in a NULL pointer dereference instead of an -EOPNOTSUPP. Fix the condition so that the availability of both callbacks is ensured. This also matches the netlink code. Note that reproducing this requires some effort - it only affects the legacy ioctl path, and needs a specific combination of driver options: - have .get_coalesce() and .coalesce_supported but no .set_coalesce(), or - have .set_coalesce() but no .get_coalesce(). Here eg. ethtool doesn't cause the crash as it first attempts to call ethtool_get_coalesce() and bails out on error.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00184 8th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.15.6, 5.16Red Hat: 4 advisoriesRed Hat: 9 fixed, 2 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
LinuxLinux5.15 and later5.15.6, 5.16Patch availableCNA
  • Linux VendorLinux Affected 5.15 and later Fixed in 5.15.6, 5.16 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*5.15 to before 5.15.6VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.15 to before 5.15.6 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.15.6, 5.16

Red Hat 4 advisories

  • RHSA-2022:8267 Released 2022-11-15 · Red Hat rating Moderate
    kernel security, bug fix, and enhancement update
    • Red Hat CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-162.6.1.el9_1
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-debug-devel-5.14.0-162.6.1.el9_1, kernel-debug-devel-matched-5.14.0-162.6.1.el9_1, kernel-devel-5.14.0-162.6.1.el9_1 +5
    • Red Hat Enterprise Linux BaseOS (v. 9) bpftool-5.14.0-162.6.1.el9_1, kernel-5.14.0-162.6.1.el9_1, kernel-abi-stablelists-5.14.0-162.6.1.el9_1 +14
  • RHSA-2022:7933 Released 2022-11-15 · Red Hat rating Moderate
    kernel-rt security and bug fix update
    • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-162.6.1.rt21.168.el9_1, kernel-rt-core-5.14.0-162.6.1.rt21.168.el9_1, kernel-rt-debug-5.14.0-162.6.1.rt21.168.el9_1 +7
    • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-162.6.1.rt21.168.el9_1, kernel-rt-core-5.14.0-162.6.1.rt21.168.el9_1, kernel-rt-debug-5.14.0-162.6.1.rt21.168.el9_1 +9
  • RHSA-2022:1988 Released 2022-05-10 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-372.9.1.el8, kernel-4.18.0-372.9.1.el8, kernel-abi-stablelists-4.18.0-372.9.1.el8 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-372.9.1.el8
Show 1 more Red Hat advisories
  • RHSA-2022:1975 Released 2022-05-10 · Red Hat rating Important
    kernel-rt security and bug fix update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-372.9.1.rt7.166.el8, kernel-rt-core-4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-4.18.0-372.9.1.rt7.166.el8 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-372.9.1.rt7.166.el8, kernel-rt-core-4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-4.18.0-372.9.1.rt7.166.el8 +7

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat CodeReady Linux Builder (v. 9)Fixed RHSA-2022:8267
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2022:8267
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2022:1988
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2022:8267
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2022:1988
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2022:1975
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2022:1975
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2022:7933
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2022:7933

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-47556

References

Patch 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