LiveActive security incident?Get immediate response
CVE Record

CVE-2021-47127: ice: track AF_XDP ZC enabled queues in bitmap

In the Linux kernel, the following vulnerability has been resolved: ice: track AF_XDP ZC enabled queues in bitmap Commit c7a219048e45 ("ice: Remove xsk_buff_pool from VSI structure") silently introduced a regression and broke the Tx side of AF_XDP in copy mode. xsk_pool on ice_ring is set only based on the existence of the XDP prog on the VSI which in turn picks ice_clean_tx_irq_zc to be executed. That is not something that should happen for copy mode as it should use the regular data path ice_clean_tx_irq. This results in a following splat when xdpsock is run in txonly or l2fwd scenarios in copy mode: <snip> [ 106.050195] BUG: kernel NULL pointer dereference, address: 0000000000000030 [ 106.057269] #PF: supervisor read access in kernel mode [ 106.062493] #PF: error_code(0x0000) - not-present page [ 106.067709] PGD 0 P4D 0 [ 106.070293] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 106.074721] CPU: 61 PID: 0 Comm: swapper/61 Not tainted 5.12.0-rc2+ #45 [ 106.081436] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [ 106.092027] RIP: 0010:xp_raw_get_dma+0x36/0x50 [ 106.096551] Code: 74 14 48 b8 ff ff ff ff ff ff 00 00 48 21 f0 48 c1 ee 30 48 01 c6 48 8b 87 90 00 00 00 48 89 f2 81 e6 ff 0f 00 00 48 c1 ea 0c <48> 8b 04 d0 48 83 e0 fe 48 01 f0 c3 66 66 2e 0f 1f 84 00 00 00 00 [ 106.115588] RSP: 0018:ffffc9000d694e50 EFLAGS: 00010206 [ 106.120893] RAX: 0000000000000000 RBX: ffff88984b8c8a00 RCX: ffff889852581800 [ 106.128137] RDX: 0000000000000006 RSI: 0000000000000000 RDI: ffff88984cd8b800 [ 106.135383] RBP: ffff888123b50001 R08: ffff889896800000 R09: 0000000000000800 [ 106.142628] R10: 0000000000000000 R11: ffffffff826060c0 R12: 00000000000000ff [ 106.149872] R13: 0000000000000000 R14: 0000000000000040 R15: ffff888123b50018 [ 106.157117] FS: 0000000000000000(0000) GS:ffff8897e0f40000(0000) knlGS:0000000000000000 [ 106.165332] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 106.171163] CR2: 0000000000000030 CR3: 000000000560a004 CR4: 00000000007706e0 [ 106.178408] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 106.185653] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 106.192898] PKRU: 55555554 [ 106.195653] Call Trace: [ 106.198143] <IRQ> [ 106.200196] ice_clean_tx_irq_zc+0x183/0x2a0 [ice] [ 106.205087] ice_napi_poll+0x3e/0x590 [ice] [ 106.209356] __napi_poll+0x2a/0x160 [ 106.212911] net_rx_action+0xd6/0x200 [ 106.216634] __do_softirq+0xbf/0x29b [ 106.220274] irq_exit_rcu+0x88/0xc0 [ 106.223819] common_interrupt+0x7b/0xa0 [ 106.227719] </IRQ> [ 106.229857] asm_common_interrupt+0x1e/0x40 </snip> Fix this by introducing the bitmap of queues that are zero-copy enabled, where each bit, corresponding to a queue id that xsk pool is being configured on, will be set/cleared within ice_xsk_pool_{en,dis}able and checked within ice_xsk_pool(). The latter is a function used for deciding which napi poll routine is executed. Idea is being taken from our other drivers such as i40e and ixgbe.

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can crash affected systems using the ice network driver with AF_XDP copy-mode transmit workloads. The public record describes a NULL pointer dereference in kernel interrupt handling, not data theft or privilege escalation. Business urgency depends on whether production hosts use the affected kernel and driver path.

Executive priority

Schedule remediation for affected network-intensive Linux hosts, especially systems where a kernel crash would disrupt services. This is not currently evidenced as actively exploited, but it can affect availability in a specific driver/workload combination.

Technical view

A regression from commit c7a219048e45 caused ice to select the zero-copy Tx cleanup path for AF_XDP copy mode. Without a configured xsk pool, ice_clean_tx_irq_zc can dereference NULL during NAPI polling. The fix tracks zero-copy-enabled queues in a bitmap and selects the correct path.

Likely exposure

Exposure appears limited to Linux systems running affected 5.12-era kernel builds with the ice driver and AF_XDP copy-mode Tx activity. The source bundle does not identify distributions, appliances, cloud images, or broader product packaging.

Exploitation context

The bundle provides a crash trace from xdpsock txonly or l2fwd copy-mode scenarios. It does not cite public exploitation, weaponized exploit availability, or CISA KEV listing. Treat this as a denial-of-service style stability risk unless vendor advisories add more impact.

Researcher notes

The source evidence is specific but narrow: Linux ice driver, AF_XDP copy mode, Tx path, NULL dereference. Version details in the bundle are sparse, so validate against upstream stable commits and downstream vendor backports before declaring systems fixed or affected.

Mitigation direction

  • Upgrade to a Linux kernel build containing the referenced stable fixes.
  • Prioritize hosts using the ice driver with AF_XDP or XDP workloads.
  • Check distribution or vendor advisories for packaged kernel status.
  • If unpatched, avoid affected AF_XDP copy-mode Tx workloads where operationally feasible.

Validation and detection

  • Inventory kernel versions against the affected 5.12-era range in the CVE record.
  • Identify hosts loading the ice network driver.
  • Confirm whether AF_XDP copy-mode Tx workloads are used.
  • Review kernel logs for NULL dereference traces involving ice_clean_tx_irq_zc or xp_raw_get_dma.
  • Verify installed kernel packages include the referenced stable fix commits.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2021-47127 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxc7a219048e459cf99c6fec0f7c1e42414e9e6202, c7a219048e459cf99c6fec0f7c1e42414e9e6202unaffected
LinuxLinux5.12, 0, 5.12.10, 5.13affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.