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CVE Record

CVE-2024-39371: io_uring: check for non-NULL file pointer in io_file_can_poll()

In the Linux kernel, the following vulnerability has been resolved: io_uring: check for non-NULL file pointer in io_file_can_poll() In earlier kernels, it was possible to trigger a NULL pointer dereference off the forced async preparation path, if no file had been assigned. The trace leading to that looks as follows: BUG: kernel NULL pointer dereference, address: 00000000000000b0 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 67 PID: 1633 Comm: buf-ring-invali Not tainted 6.8.0-rc3+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 2/2/2022 RIP: 0010:io_buffer_select+0xc3/0x210 Code: 00 00 48 39 d1 0f 82 ae 00 00 00 48 81 4b 48 00 00 01 00 48 89 73 70 0f b7 50 0c 66 89 53 42 85 ed 0f 85 d2 00 00 00 48 8b 13 <48> 8b 92 b0 00 00 00 48 83 7a 40 00 0f 84 21 01 00 00 4c 8b 20 5b RSP: 0018:ffffb7bec38c7d88 EFLAGS: 00010246 RAX: ffff97af2be61000 RBX: ffff97af234f1700 RCX: 0000000000000040 RDX: 0000000000000000 RSI: ffff97aecfb04820 RDI: ffff97af234f1700 RBP: 0000000000000000 R08: 0000000000200030 R09: 0000000000000020 R10: ffffb7bec38c7dc8 R11: 000000000000c000 R12: ffffb7bec38c7db8 R13: ffff97aecfb05800 R14: ffff97aecfb05800 R15: ffff97af2be5e000 FS: 00007f852f74b740(0000) GS:ffff97b1eeec0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000b0 CR3: 000000016deab005 CR4: 0000000000370ef0 Call Trace: <TASK> ? __die+0x1f/0x60 ? page_fault_oops+0x14d/0x420 ? do_user_addr_fault+0x61/0x6a0 ? exc_page_fault+0x6c/0x150 ? asm_exc_page_fault+0x22/0x30 ? io_buffer_select+0xc3/0x210 __io_import_iovec+0xb5/0x120 io_readv_prep_async+0x36/0x70 io_queue_sqe_fallback+0x20/0x260 io_submit_sqes+0x314/0x630 __do_sys_io_uring_enter+0x339/0xbc0 ? __do_sys_io_uring_register+0x11b/0xc50 ? vm_mmap_pgoff+0xce/0x160 do_syscall_64+0x5f/0x180 entry_SYSCALL_64_after_hwframe+0x46/0x4e RIP: 0033:0x55e0a110a67e Code: ba cc 00 00 00 45 31 c0 44 0f b6 92 d0 00 00 00 31 d2 41 b9 08 00 00 00 41 83 e2 01 41 c1 e2 04 41 09 c2 b8 aa 01 00 00 0f 05 <c3> 90 89 30 eb a9 0f 1f 40 00 48 8b 42 20 8b 00 a8 06 75 af 85 f6 because the request is marked forced ASYNC and has a bad file fd, and hence takes the forced async prep path. Current kernels with the request async prep cleaned up can no longer hit this issue, but for ease of backporting, let's add this safety check in here too as it really doesn't hurt. For both cases, this will inevitably end with a CQE posted with -EBADF.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2024-39371 is a Linux kernel io_uring bug where a malformed request with a bad file descriptor could hit a NULL pointer dereference. The public record describes a kernel crash path, not data theft or remote compromise. Business urgency depends on whether untrusted local users or workloads can run code on affected Linux hosts.

Executive priority

Patch during the next normal kernel maintenance window, sooner for shared hosts running untrusted workloads. There is no cited evidence of active exploitation, but kernel crash bugs can disrupt service and are costly on production infrastructure.

Technical view

The issue is in io_file_can_poll()/forced async preparation. Earlier kernels could process an io_uring request marked forced ASYNC with no assigned file, leading to a NULL pointer dereference during buffer selection. The fix adds a non-NULL file check; the expected safe result is a completion queue entry with -EBADF.

Likely exposure

Exposure is most relevant on Linux systems using affected kernel versions or backports where untrusted local code can invoke io_uring. Public sources do not show remote attack surface, affected distributions beyond the cited Debian advisory, or a complete affected-version matrix.

Exploitation context

The CVE is not listed as KEV, and the bundle provides no evidence of active exploitation. The described trigger requires a crafted local io_uring request involving forced async preparation and a bad file descriptor. Treat this primarily as a local stability and availability risk unless vendor guidance says otherwise.

Researcher notes

Evidence supports a NULL pointer dereference in the io_uring forced async path, resolved by checking for a non-NULL file pointer. The source bundle does not provide CVSS, CWE, exploit status, or complete downstream package mapping, so validation should rely on vendor kernel changelogs and distribution advisories.

Mitigation direction

  • Update to vendor kernel packages containing the referenced stable fixes.
  • Prioritize shared, multi-user, CI, and workload-hosting Linux systems.
  • Check Debian LTS guidance if running Debian LTS kernels.
  • Where patching is delayed, review vendor-supported io_uring restriction options.
  • Track distribution advisories for exact fixed package versions.

Validation and detection

  • Inventory Linux kernel versions across affected assets.
  • Confirm whether installed kernels include the referenced stable commits or vendor backports.
  • Review distro advisories for matching package fixed versions.
  • Assess whether untrusted local users or workloads can access io_uring.
  • Monitor kernel logs for NULL dereference or oops events involving io_uring.
Prepared
Confidence
medium
Sources
7

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-2024-39371 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
6Source 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
LinuxLinuxa76c0b31eef50fdb8b21d53a6d050f59241fb88e, a76c0b31eef50fdb8b21d53a6d050f59241fb88e, a76c0b31eef50fdb8b21d53a6d050f59241fb88e, a76c0b31eef50fdb8b21d53a6d050f59241fb88eunaffected
LinuxLinux5.19, 0, 6.1.95, 6.6.35, 6.9.5, 6.10affected
Weakness

CWE details

No CWE listed

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