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CVE Record

CVE-2021-47197: net/mlx5e: nullify cq->dbg pointer in mlx5_debug_cq_remove()

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: nullify cq->dbg pointer in mlx5_debug_cq_remove() Prior to this patch in case mlx5_core_destroy_cq() failed it proceeds to rest of destroy operations. mlx5_core_destroy_cq() could be called again by user and cause additional call of mlx5_debug_cq_remove(). cq->dbg was not nullify in previous call and cause the crash. Fix it by nullify cq->dbg pointer after removal. Also proceed to destroy operations only if FW return 0 for MLX5_CMD_OP_DESTROY_CQ command. general protection fault, probably for non-canonical address 0x2000300004058: 0000 [#1] SMP PTI CPU: 5 PID: 1228 Comm: python Not tainted 5.15.0-rc5_for_upstream_min_debug_2021_10_14_11_06 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:lockref_get+0x1/0x60 Code: 5d e9 53 ff ff ff 48 8d 7f 70 e8 0a 2e 48 00 c7 85 d0 00 00 00 02 00 00 00 c6 45 70 00 fb 5d c3 c3 cc cc cc cc cc cc cc cc 53 <48> 8b 17 48 89 fb 85 d2 75 3d 48 89 d0 bf 64 00 00 00 48 89 c1 48 RSP: 0018:ffff888137dd7a38 EFLAGS: 00010206 RAX: 0000000000000000 RBX: ffff888107d5f458 RCX: 00000000fffffffe RDX: 000000000002c2b0 RSI: ffffffff8155e2e0 RDI: 0002000300004058 RBP: ffff888137dd7a88 R08: 0002000300004058 R09: ffff8881144a9f88 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881141d4000 R13: ffff888137dd7c68 R14: ffff888137dd7d58 R15: ffff888137dd7cc0 FS: 00007f4644f2a4c0(0000) GS:ffff8887a2d40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b4500f4380 CR3: 0000000114f7a003 CR4: 0000000000170ea0 Call Trace: simple_recursive_removal+0x33/0x2e0 ? debugfs_remove+0x60/0x60 debugfs_remove+0x40/0x60 mlx5_debug_cq_remove+0x32/0x70 [mlx5_core] mlx5_core_destroy_cq+0x41/0x1d0 [mlx5_core] devx_obj_cleanup+0x151/0x330 [mlx5_ib] ? __pollwait+0xd0/0xd0 ? xas_load+0x5/0x70 ? xa_load+0x62/0xa0 destroy_hw_idr_uobject+0x20/0x80 [ib_uverbs] uverbs_destroy_uobject+0x3b/0x360 [ib_uverbs] uobj_destroy+0x54/0xa0 [ib_uverbs] ib_uverbs_cmd_verbs+0xaf2/0x1160 [ib_uverbs] ? uverbs_finalize_object+0xd0/0xd0 [ib_uverbs] ib_uverbs_ioctl+0xc4/0x1b0 [ib_uverbs] __x64_sys_ioctl+0x3e4/0x8e0

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-47197 is a Linux kernel crash issue in the mlx5 networking/RDMA driver cleanup path. If a completion queue destroy operation fails and cleanup is attempted again, a stale debugfs pointer can be reused and crash the kernel. Business impact is mainly availability on affected Linux hosts using this driver path.

Executive priority

Treat as a targeted availability risk, not a broad internet-facing emergency based on current evidence. Patch through normal kernel update channels, prioritizing production systems with mlx5/RDMA usage or workloads where host crashes have high operational impact.

Technical view

The bug is in mlx5_debug_cq_remove() and mlx5_core_destroy_cq(). The source says cq->dbg was not nullified after removal, so a later destroy call could remove the same debugfs object again and trigger a general protection fault. The fix nullifies cq->dbg and only continues destroy operations when firmware reports successful CQ destruction.

Likely exposure

Exposure appears limited to affected Linux kernels running mlx5-related networking/RDMA paths. The bundle lists Linux kernel versions including 5.15, 5.10.82, 5.15.5, and 5.16 as affected, but distro backports may change real-world status.

Exploitation context

The bundle does not report active exploitation, and KEV is false. The crash trace involves ib_uverbs ioctl activity and mlx5_ib cleanup, but the provided sources do not establish a practical exploit path, privilege requirement, or remote attack scenario.

Researcher notes

Evidence is source-limited. The CVE text gives a crash trace and fix rationale, but no CVSS, CWE, exploitability assessment, or attacker prerequisites. Analysis should focus on affected kernel lineage, distro backports, mlx5 driver use, and whether user-accessible RDMA/uverbs paths are enabled.

Mitigation direction

  • Update affected Linux kernels to vendor or distro builds containing the stable fixes.
  • Prioritize hosts using mlx5 networking, RDMA, or ib_uverbs functionality.
  • Check Linux vendor guidance for supported mitigations if patching is delayed.
  • Avoid direct wrangler or deployment assumptions; this is kernel maintenance work.

Validation and detection

  • Inventory running kernel versions against vendor security advisories and changelogs.
  • Check whether mlx5_core, mlx5_ib, or ib_uverbs are used on critical hosts.
  • Verify the kernel includes one of the referenced stable commits or an equivalent backport.
  • Confirm no unexplained kernel crashes match the mlx5/debugfs cleanup trace.
Prepared
Confidence
medium
Sources
5

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

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CVE-2021-47197 mapping review

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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
4Source 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4f7bddf8c5c01cac74373443b13a68e1c6723a94, 94b960b9deffc02fc0747afc01f72cc62ab099e3, 94b960b9deffc02fc0747afc01f72cc62ab099e3, ed8aafea4fec9c654e63445236e0b505e27ed3a7unaffected
LinuxLinux5.15, 0, 5.10.82, 5.15.5, 5.16affected
Weakness

CWE details

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