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CVE-2025-40009— fs/proc/task_mmu: check p->vec_buf for NULL

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未检查p->vec_buf是否为NULL，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Easy EPSS 0.24% · P15

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 52526ca7fdb905a768a93f8faa418e9b988fc34b< ca988dcdc6683ecd9de5f525ce469588a9141c21 affected
52526ca7fdb905a768a93f8faa418e9b988fc34b< a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3 affected
52526ca7fdb905a768a93f8faa418e9b988fc34b< 28aa29986dde79e8466bc87569141291053833f5 affected
6.7 affected
< 6.7 unaffected
6.12.50≤ 6.12.* unaffected
6.16.10≤ 6.16.* unaffected
6.17≤ * unaffected
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I. Basic Information for CVE-2025-40009

Vulnerability Information
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Vulnerability Title
fs/proc/task_mmu: check p->vec_buf for NULL
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: fs/proc/task_mmu: check p->vec_buf for NULL When the PAGEMAP_SCAN ioctl is invoked with vec_len = 0 reaches pagemap_scan_backout_range(), kernel panics with null-ptr-deref: [ 44.936808] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.937797] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 44.938391] CPU: 1 UID: 0 PID: 2480 Comm: reproducer Not tainted 6.17.0-rc6 #22 PREEMPT(none) [ 44.939062] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.939935] RIP: 0010:pagemap_scan_thp_entry.isra.0+0x741/0xa80 <snip registers, unreliable trace> [ 44.946828] Call Trace: [ 44.947030] <TASK> [ 44.949219] pagemap_scan_pmd_entry+0xec/0xfa0 [ 44.952593] walk_pmd_range.isra.0+0x302/0x910 [ 44.954069] walk_pud_range.isra.0+0x419/0x790 [ 44.954427] walk_p4d_range+0x41e/0x620 [ 44.954743] walk_pgd_range+0x31e/0x630 [ 44.955057] __walk_page_range+0x160/0x670 [ 44.956883] walk_page_range_mm+0x408/0x980 [ 44.958677] walk_page_range+0x66/0x90 [ 44.958984] do_pagemap_scan+0x28d/0x9c0 [ 44.961833] do_pagemap_cmd+0x59/0x80 [ 44.962484] __x64_sys_ioctl+0x18d/0x210 [ 44.962804] do_syscall_64+0x5b/0x290 [ 44.963111] entry_SYSCALL_64_after_hwframe+0x76/0x7e vec_len = 0 in pagemap_scan_init_bounce_buffer() means no buffers are allocated and p->vec_buf remains set to NULL. This breaks an assumption made later in pagemap_scan_backout_range(), that page_region is always allocated for p->vec_buf_index. Fix it by explicitly checking p->vec_buf for NULL before dereferencing. Other sites that might run into same deref-issue are already (directly or transitively) protected by checking p->vec_buf. Note: From PAGEMAP_SCAN man page, it seems vec_len = 0 is valid when no output is requested and it's only the side effects caller is interested in, hence it passes check in pagemap_scan_get_args(). This issue was found by syzkaller.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未检查p->vec_buf是否为NULL，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 52526ca7fdb905a768a93f8faa418e9b988fc34b ~ ca988dcdc6683ecd9de5f525ce469588a9141c21 -
Linux Linux 6.7 -

II. Public POCs for CVE-2025-40009

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III. Intelligence Information for CVE-2025-40009

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Same Patch Batch · Linux · 2025-10-20 · 13 CVEs total

CVE-2025-40012 7.8 HIGH net/smc: fix warning in smc_rx_splice() when calling get_page()
CVE-2025-40006 7.8 HIGH mm/hugetlb: fix folio is still mapped when deleted
CVE-2025-40017 media: iris: Fix memory leak by freeing untracked persist buffer
CVE-2025-40015 media: stm32-csi: Fix dereference before NULL check
CVE-2025-40016 media: uvcvideo: Mark invalid entities with id UVC_INVALID_ENTITY_ID
CVE-2025-40013 ASoC: qcom: audioreach: fix potential null pointer dereference
CVE-2025-40011 drm/gma500: Fix null dereference in hdmi teardown
CVE-2025-40010 afs: Fix potential null pointer dereference in afs_put_server
CVE-2025-40008 kmsan: fix out-of-bounds access to shadow memory
CVE-2025-40007 netfs: fix reference leak
CVE-2025-40005 spi: cadence-quadspi: Implement refcount to handle unbind during busy
CVE-2025-40004 net/9p: Fix buffer overflow in USB transport layer

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-40009

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