Linux Kernel up to 6.17.1 KASAN p9_read_work race condition

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4.4$0-$5k0.00

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.17.1. This impacts the function p9_read_work of the component KASAN. Such manipulation leads to race condition. This vulnerability is listed as CVE-2025-40027. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.17.1. It has been rated as critical. Affected by this issue is the function p9_read_work of the component KASAN. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/9p: fix double req put in p9_fd_cancelled Syzkaller reports a KASAN issue as below: general protection fault, probably for non-canonical address 0xfbd59c0000000021: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: maybe wild-memory-access in range [0xdead000000000108-0xdead00000000010f] CPU: 0 PID: 5083 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00037-g855bd1d7d838 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:__list_del include/linux/list.h:114 [inline] RIP: 0010:__list_del_entry include/linux/list.h:137 [inline] RIP: 0010:list_del include/linux/list.h:148 [inline] RIP: 0010:p9_fd_cancelled+0xe9/0x200 net/9p/trans_fd.c:734 Call Trace: <TASK> p9_client_flush+0x351/0x440 net/9p/client.c:614 p9_client_rpc+0xb6b/0xc70 net/9p/client.c:734 p9_client_version net/9p/client.c:920 [inline] p9_client_create+0xb51/0x1240 net/9p/client.c:1027 v9fs_session_init+0x1f0/0x18f0 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xcb0 fs/9p/vfs_super.c:126 legacy_get_tree+0x108/0x220 fs/fs_context.c:632 vfs_get_tree+0x8e/0x300 fs/super.c:1573 do_new_mount fs/namespace.c:3056 [inline] path_mount+0x6a6/0x1e90 fs/namespace.c:3386 do_mount fs/namespace.c:3399 [inline] __do_sys_mount fs/namespace.c:3607 [inline] __se_sys_mount fs/namespace.c:3584 [inline] __x64_sys_mount+0x283/0x300 fs/namespace.c:3584 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 This happens because of a race condition between: - The 9p client sending an invalid flush request and later cleaning it up; - The 9p client in p9_read_work() canceled all pending requests. Thread 1 Thread 2 ... p9_client_create() ... p9_fd_create() ... p9_conn_create() ... // start Thread 2 INIT_WORK(&m->rq, p9_read_work); p9_read_work() ... p9_client_rpc() ... ... p9_conn_cancel() ... spin_lock(&m->req_lock); ... p9_fd_cancelled() ... ... spin_unlock(&m->req_lock); // status rewrite p9_client_cb(m->client, req, REQ_STATUS_ERROR) // first remove list_del(&req->req_list); ... spin_lock(&m->req_lock) ... // second remove list_del(&req->req_list); spin_unlock(&m->req_lock) ... Commit 74d6a5d56629 ("9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work") fixes a concurrency issue in the 9p filesystem client where the req_list could be deleted simultaneously by both p9_read_work and p9_fd_cancelled functions, but for the case where req->status equals REQ_STATUS_RCVD. Update the check for req->status in p9_fd_cancelled to skip processing not just received requests, but anything that is not SENT, as whatever changed the state from SENT also removed the request from its list. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. [updated the check from status == RECV || status == ERROR to status != SENT]

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2025-40027 since 04/16/2025. The exploitation is known to be difficult. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 271872 (Linux Distros Unpatched Vulnerability : CVE-2025-40027), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.195, 6.1.156, 6.6.111, 6.12.52, 6.16.12, 6.17.2 or 6.18-rc1 eliminates this vulnerability. Applying the patch c1db864270eb7fea94a9ef201da0c9dc1cbab7b8/0e0097005abc02c9f262370674f855625f4f3fb4/284e67a93b8c48952b6fc82129a8d3eb9dc73b06/716dceb19a9f8ff6c9d3aee5a771a93d6a47a0b6/448db01a48e1cdbbc31c995716a5dac1e52ba036/94797b84cb9985022eb9cb3275c9497fbc883bb6/674b56aa57f9379854cb6798c3bbcef7e7b51ab7 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (271872) and CERT Bund (WID-SEC-2025-2430). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • NetApp ActiveIQ Unified Manager
  • Open Source Linux Kernel
  • Microsoft Azure

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.6
VulDB Meta Temp Score: 4.4

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 271872
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40027

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.195/6.1.156/6.6.111/6.12.52/6.16.12/6.17.2/6.18-rc1
Patch: c1db864270eb7fea94a9ef201da0c9dc1cbab7b8/0e0097005abc02c9f262370674f855625f4f3fb4/284e67a93b8c48952b6fc82129a8d3eb9dc73b06/716dceb19a9f8ff6c9d3aee5a771a93d6a47a0b6/448db01a48e1cdbbc31c995716a5dac1e52ba036/94797b84cb9985022eb9cb3275c9497fbc883bb6/674b56aa57f9379854cb6798c3bbcef7e7b51ab7

Timelineinfo

04/16/2025 CVE reserved
10/28/2025 +195 days Advisory disclosed
10/28/2025 +0 days VulDB entry created
02/27/2026 +122 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40027 (🔒)
GCVE (CVE): GCVE-0-2025-40027
GCVE (VulDB): GCVE-100-330218
CERT Bund: WID-SEC-2025-2430 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 10/28/2025 11:22
Updated: 02/27/2026 21:05
Changes: 10/28/2025 11:22 (59), 10/28/2025 11:34 (1), 10/28/2025 15:43 (7), 10/30/2025 14:45 (2), 12/03/2025 15:59 (1), 12/22/2025 02:00 (1), 02/12/2026 16:56 (1), 02/27/2026 21:05 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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