LiveActive security incident?Get immediate response
CVE Record

CVE-2021-47481: RDMA/mlx5: Initialize the ODP xarray when creating an ODP MR

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Initialize the ODP xarray when creating an ODP MR Normally the zero fill would hide the missing initialization, but an errant set to desc_size in reg_create() causes a crash: BUG: unable to handle page fault for address: 0000000800000000 PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 890 Comm: ib_write_bw Not tainted 5.15.0-rc4+ #47 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5_ib_dereg_mr+0x14/0x3b0 [mlx5_ib] Code: 48 63 cd 4c 89 f7 48 89 0c 24 e8 37 30 03 e1 48 8b 0c 24 eb a0 90 0f 1f 44 00 00 41 56 41 55 41 54 55 53 48 89 fb 48 83 ec 30 <48> 8b 2f 65 48 8b 04 25 28 00 00 00 48 89 44 24 28 31 c0 8b 87 c8 RSP: 0018:ffff88811afa3a60 EFLAGS: 00010286 RAX: 000000000000001c RBX: 0000000800000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000800000000 RBP: 0000000800000000 R08: 0000000000000000 R09: c0000000fffff7ff R10: ffff88811afa38f8 R11: ffff88811afa38f0 R12: ffffffffa02c7ac0 R13: 0000000000000000 R14: ffff88811afa3cd8 R15: ffff88810772fa00 FS: 00007f47b9080740(0000) GS:ffff88852cd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000800000000 CR3: 000000010761e003 CR4: 0000000000370ea0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mlx5_ib_free_odp_mr+0x95/0xc0 [mlx5_ib] mlx5_ib_dereg_mr+0x128/0x3b0 [mlx5_ib] ib_dereg_mr_user+0x45/0xb0 [ib_core] ? xas_load+0x8/0x80 destroy_hw_idr_uobject+0x1a/0x50 [ib_uverbs] uverbs_destroy_uobject+0x2f/0x150 [ib_uverbs] uobj_destroy+0x3c/0x70 [ib_uverbs] ib_uverbs_cmd_verbs+0x467/0xb00 [ib_uverbs] ? uverbs_finalize_object+0x60/0x60 [ib_uverbs] ? ttwu_queue_wakelist+0xa9/0xe0 ? pty_write+0x85/0x90 ? file_tty_write.isra.33+0x214/0x330 ? process_echoes+0x60/0x60 ib_uverbs_ioctl+0xa7/0x110 [ib_uverbs] __x64_sys_ioctl+0x10d/0x8e0 ? vfs_write+0x17f/0x260 do_syscall_64+0x3c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Add the missing xarray initialization and remove the desc_size set.

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 bug can crash systems using Mellanox mlx5 RDMA with on-demand paging memory registration. The source describes a kernel page fault during RDMA memory-region cleanup. Business urgency depends on whether affected kernels and RDMA hardware/features are deployed in production workloads.

Executive priority

Prioritize patching on RDMA-enabled compute, storage, HPC, or low-latency hosts where a kernel crash would disrupt production. For general servers without mlx5 RDMA use, urgency is lower but still track through normal kernel update cycles.

Technical view

The mlx5 RDMA driver failed to initialize an ODP xarray when creating an ODP memory region. A related desc_size assignment could expose the bad state, leading to a page fault in mlx5_ib_dereg_mr during user verbs object destruction.

Likely exposure

Exposure is most likely on Linux systems running affected 5.13, 5.14.16, or 5.15-era kernels with mlx5 RDMA, ib_uverbs access, and ODP memory-region use. Systems without mlx5 RDMA or RDMA user verbs are less likely exposed based on the provided sources.

Exploitation context

The bundle does not show CISA KEV listing, active exploitation, public exploit code, or remote exploitability. The evidence shows a reproducible kernel crash path in RDMA workloads, which is most relevant to availability risk on specialized hosts.

Researcher notes

The source evidence supports a denial-of-service style kernel crash in a narrow driver path. It does not provide CVSS, CWE, exploit maturity, or full affected-version semantics beyond listed kernel versions and fixing commits.

Mitigation direction

  • Update to a vendor kernel containing the referenced upstream stable fixes.
  • Check vendor advisories for exact backported package versions.
  • Restrict RDMA user verbs device access to trusted users where feasible.
  • Disable unused mlx5 RDMA functionality if operationally safe.
  • Monitor for kernel oops traces involving mlx5_ib_dereg_mr.

Validation and detection

  • Inventory kernels on systems with Mellanox mlx5 RDMA hardware.
  • Confirm whether ib_uverbs and mlx5_ib are loaded or available.
  • Compare installed kernel sources or changelogs against the referenced commits.
  • Review logs for page faults in mlx5_ib_dereg_mr or ODP cleanup.
  • Validate vendor kernel packages include the stable fixes.
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-2021-47481 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxa639e66703ee45745dc4057c7c2013ed9e1963a7, a639e66703ee45745dc4057c7c2013ed9e1963a7, 29f91bd26f3ba828a55cb446ecd44caacf0df026unaffected
LinuxLinux5.13, 0, 5.14.16, 5.15affected
Weakness

CWE details

No CWE listed

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