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CVE Record

CVE-2024-39500: sock_map: avoid race between sock_map_close and sk_psock_put

In the Linux kernel, the following vulnerability has been resolved: sock_map: avoid race between sock_map_close and sk_psock_put sk_psock_get will return NULL if the refcount of psock has gone to 0, which will happen when the last call of sk_psock_put is done. However, sk_psock_drop may not have finished yet, so the close callback will still point to sock_map_close despite psock being NULL. This can be reproduced with a thread deleting an element from the sock map, while the second one creates a socket, adds it to the map and closes it. That will trigger the WARN_ON_ONCE: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701 Modules linked in: CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701 Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02 RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293 RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000 RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0 RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3 R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840 R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870 FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0 Call Trace: <TASK> unix_release+0x87/0xc0 net/unix/af_unix.c:1048 __sock_release net/socket.c:659 [inline] sock_close+0xbe/0x240 net/socket.c:1421 __fput+0x42b/0x8a0 fs/file_table.c:422 __do_sys_close fs/open.c:1556 [inline] __se_sys_close fs/open.c:1541 [inline] __x64_sys_close+0x7f/0x110 fs/open.c:1541 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb37d618070 Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070 RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> Use sk_psock, which will only check that the pointer is not been set to NULL yet, which should only happen after the callbacks are restored. If, then, a reference can still be gotten, we may call sk_psock_stop and cancel psock->work. As suggested by Paolo Abeni, reorder the condition so the control flow is less convoluted. After that change, the reproducer does not trigger the WARN_ON_ONCE anymore.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A timing flaw in Linux socket-map cleanup can leave a socket callback referring to an object whose reference count has reached zero. A local, low-privileged user may be able to trigger the race. The supplied CVSS assessment indicates potentially severe confidentiality, integrity, and availability impact, although the public description demonstrates a kernel warning rather than confirmed real-world compromise.

Executive priority

Treat this as a high-priority kernel maintenance issue on shared or otherwise locally exposed Linux systems. It is not documented as remotely or actively exploited, so prioritize verified vulnerable hosts over emergency internet-edge response. Use distribution-supported updates and confirm the fixed kernel is actually running.

Technical view

A race exists between sock_map_close and sk_psock_put. sk_psock_get may return NULL after the psock reference count reaches zero while sk_psock_drop has not finished and the close callback still targets sock_map_close. Concurrent map deletion and socket creation, insertion, and closure reproduced the warning. The kernel fix changes psock handling and cancels pending work when a reference remains available.

Likely exposure

Exposure is limited to Linux kernels containing the vulnerable sock-map code and environments where a local low-privileged user can exercise the relevant socket-map operations. The supplied version data names affected release points including 5.13, 5.15.162, 6.1.95, 6.6.35, 6.9.6, and 6.10, but its formatting is ambiguous; confirm status through the distribution vendor.

Exploitation context

The CVSS vector is local, low complexity, low privileges, and no user interaction. A concurrent reproducer triggered WARN_ON_ONCE, establishing reproducibility of the race. The bundle marks the CVE as absent from KEV and provides no evidence of active exploitation, a public weaponized exploit, or remote attackability.

Researcher notes

The demonstrated trigger requires one thread deleting a sock-map element while another creates, inserts, and closes a socket. The core issue is callback restoration lagging behind psock reference-count exhaustion. The supplied record does not identify a CWE or conclusively document the practical impact beyond the warning; CVSS impact claims should therefore be treated as assessment, not demonstrated outcome.

Mitigation direction

  • Apply a vendor-supported kernel update that incorporates the applicable stable fix.
  • Review Linux distribution advisories because release numbering and backport status may differ.
  • Prioritize multi-user systems where untrusted local users can access relevant socket-map functionality.
  • Reboot into the updated kernel when required by the operating-system vendor.

Validation and detection

  • Inventory running kernel releases across Linux hosts and compare them with vendor advisories.
  • Confirm the installed kernel changelog references CVE-2024-39500 or an applicable stable fix commit.
  • Verify systems are running the updated kernel after installation and reboot.
  • Review kernel logs for sock_map_close warnings, while recognizing absence does not prove safety.
Prepared
Confidence
high
Sources
8

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-2024-39500 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
2ADP providers
7Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-39500Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
LinuxLinuxaadb2bb83ff789de63b48b4edeab7329423a50d3, aadb2bb83ff789de63b48b4edeab7329423a50d3, aadb2bb83ff789de63b48b4edeab7329423a50d3, aadb2bb83ff789de63b48b4edeab7329423a50d3, aadb2bb83ff789de63b48b4edeab7329423a50d3, c4896f5fd83664a50ac4fef4131a265d15734e5a, 5.10.248unaffected
LinuxLinux5.13, 0, 5.15.162, 6.1.95, 6.6.35, 6.9.6, 6.10affected
Weakness

CWE details

No CWE listed

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