Description
In the Linux kernel, the following vulnerability has been resolved:

nvme: fix cdev lifetime

Sashiko bot reported a potential problem for the cdev lifetime in [0]
- the code there is heavily based on the NVMe code.

Currently the NS head .open and .release file_operations methods take and
put a reference to the nvme_ns_head to ensure that this structure does not
disappear while we open fds for that cdev.

In multipath mode, when we teardown the NS head, we call nvme_cdev_del() ->
cdev_device_del() -> cdev_del(). However after cdev_del() returns, cdevs
already open will remain and their fops will still be callable. As such,
we can still reference the cdev after the nvme_ns_head reference count
drops to 0 (and is freed).

This can be shown with an application which delays between opening the cdev
and issuing the ioctl while the NS head is being torn down:

# ./ioctl_file /dev/ng1n1 &
# waiting 10 seconds ....

# ./ini_nvme_teardown.sh
[ 21.221718] nvme nvme1: Removing ctrl: NQN "nvme-test-target"
[ 21.274609] nvme nvme2: Removing ctrl: NQN "nvme-test-target"
# now going to issue ioctl ....
[ 26.549285] ==================================================================
[ 26.550841] BUG: KASAN: slab-use-after-free in cdev_put.part.0+0x3d/0x40
[ 26.552352] Read of size 8 at addr ffff88811e7fa170 by task ioctl_file/237
[ 26.553805]
[ 26.554227] CPU: 3 UID: 0 PID: 237 Comm: ioctl_file Not tainted 7.2.0-rc1-00004-g6852a10e32d4 #921 PREEMPT(lazy)
[ 26.554236] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 26.554241] Call Trace:
[ 26.554245] <TASK>
[ 26.554248] dump_stack_lvl+0x68/0xa0
[ 26.554266] print_report+0x10d/0x5d0
[ 26.554276] ? __virt_addr_valid+0x21d/0x3f0
[ 26.554287] ? cdev_put.part.0+0x3d/0x40
[ 26.554292] kasan_report+0x96/0xd0
[ 26.554300] ? cdev_put.part.0+0x3d/0x40
[ 26.554307] cdev_put.part.0+0x3d/0x40
[ 26.554313] __fput+0x7bc/0xa70
[ 26.554322] fput_close_sync+0xd8/0x190
[ 26.554328] ? __pfx_fput_close_sync+0x10/0x10
[ 26.554337] __x64_sys_close+0x79/0xd0
[ 26.554344] do_syscall_64+0x117/0x6b0
[ 26.554351] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 26.554358] RIP: 0033:0x7f938c067727
[ 26.554364] Code: 48 89 fa 4c 89 df e8 28 ad 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5bf
[ 26.554369] RSP: 002b:00007fff49f05980 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
[ 26.554376] RAX: ffffffffffffffda RBX: 00007f938bfd7780 RCX: 00007f938c067727
[ 26.554380] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
[ 26.554383] RBP: 00007fff49f05a10 R08: 0000000000000000 R09: 0000000000000000
[ 26.554386] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
[ 26.554389] R13: 00007fff49f05b40 R14: 00007f938c207000 R15: 000055c148471d78
[ 26.554397] </TASK>
[ 26.554399]
[ 26.575612] Allocated by task 100:
[ 26.575871] kasan_save_stack+0x24/0x50
[ 26.576157] kasan_save_track+0x14/0x30
[ 26.576418] __kasan_kmalloc+0x7f/0x90
[ 26.576668] __kmalloc_noprof+0x281/0x6c0
[ 26.576938] nvme_alloc_ns+0x7f7/0x3170
[ 26.577206] nvme_scan_ns+0x508/0x880
[ 26.577449] async_run_entry_fn+0x8c/0x350
[ 26.577723] process_scheduled_works+0xb6f/0x1a00
[ 26.578034] worker_thread+0x4ad/0xb40
[ 26.578283] kthread+0x34f/0x450
[ 26.578501] ret_from_fork+0x563/0x800
[ 26.578752] ret_from_fork_asm+0x1a/0x30
[ 26.579012]
[ 26.579124] Freed by task 237:
[ 26.579335] kasan_save_stack+0x24/0x50
[ 26.579596] kasan_save_track+0x14/0x30
[ 26.579855] kasan_save_free_info+0x3a/0x60
[ 26.580131] __kasan_slab_free+0x43/0x70
[ 26.580388] kfree+0x321/0x500
[ 26.580591] nvme_ns_head_chr_release+0x39/0x50
[ 26.580883] __fput+0x352/0xa70
[ 26.581095] fput_close_sync+0xd8/0x190
[ 26.581350] __x64_sys_close+0x79/0xd0
[ 26.581595] do_syscall_64+0x117/0x6b0
[ 26.581842] entry_SYSCAL
---truncated---
Published: 2026-10-18
Score: 4.1 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Use‑After‑Free leading to kernel crash
Action: Patch Now
AI Analysis

Impact

The kernel bug allows a use‑after‑free of a character device instance when the NVMe namespace head is torn down while file descriptors to the device remain open. An attacker who can open the NVMe device file and then trigger a controller removal can cause a kernel panic, potentially leading to denial of service. The weakness arises from incorrect reference counting of the cdev structure, exactly the type of flaw classified as a use‑after‑free.

Affected Systems

Any Linux kernel that has not incorporated the cdev lifetime fix. The vulnerability applies to all distributions that ship the affected kernel code, regardless of version, until the patch is applied.

Risk and Exploitability

The flaw is a kernel defect that can crash the operating system. The CVSS score is 4.1, indicating a moderate impact. The EPSS score is < 1%, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is local or system‑level via an application holding a file descriptor open to the NVMe device while the controller is removed. Exploitation requires the ability to open the device and trigger the teardown sequence, which are typically privileges of the user running the application.

Generated by OpenCVE AI on October 24, 2026 at 04:56 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Install the kernel update containing the NVMe cdev lifetime patch as soon as possible.
  • If the patch cannot be applied immediately, ensure that no NVMe device file descriptors remain open before removing or reinitializing the controller or multipath setup.
  • In general, update to the latest stable Linux kernel and reboot to complete the update.

Generated by OpenCVE AI on October 24, 2026 at 04:56 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Sat, 24 Oct 2026 03:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Sat, 24 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

 cvssV3_1

{'score': 4.1, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Sun, 18 Oct 2026 21:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Sun, 18 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: nvme: fix cdev lifetime Sashiko bot reported a potential problem for the cdev lifetime in [0] - the code there is heavily based on the NVMe code. Currently the NS head .open and .release file_operations methods take and put a reference to the nvme_ns_head to ensure that this structure does not disappear while we open fds for that cdev. In multipath mode, when we teardown the NS head, we call nvme_cdev_del() -> cdev_device_del() -> cdev_del(). However after cdev_del() returns, cdevs already open will remain and their fops will still be callable. As such, we can still reference the cdev after the nvme_ns_head reference count drops to 0 (and is freed). This can be shown with an application which delays between opening the cdev and issuing the ioctl while the NS head is being torn down: # ./ioctl_file /dev/ng1n1 & # waiting 10 seconds .... # ./ini_nvme_teardown.sh [ 21.221718] nvme nvme1: Removing ctrl: NQN "nvme-test-target" [ 21.274609] nvme nvme2: Removing ctrl: NQN "nvme-test-target" # now going to issue ioctl .... [ 26.549285] ================================================================== [ 26.550841] BUG: KASAN: slab-use-after-free in cdev_put.part.0+0x3d/0x40 [ 26.552352] Read of size 8 at addr ffff88811e7fa170 by task ioctl_file/237 [ 26.553805] [ 26.554227] CPU: 3 UID: 0 PID: 237 Comm: ioctl_file Not tainted 7.2.0-rc1-00004-g6852a10e32d4 #921 PREEMPT(lazy) [ 26.554236] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 26.554241] Call Trace: [ 26.554245] <TASK> [ 26.554248] dump_stack_lvl+0x68/0xa0 [ 26.554266] print_report+0x10d/0x5d0 [ 26.554276] ? __virt_addr_valid+0x21d/0x3f0 [ 26.554287] ? cdev_put.part.0+0x3d/0x40 [ 26.554292] kasan_report+0x96/0xd0 [ 26.554300] ? cdev_put.part.0+0x3d/0x40 [ 26.554307] cdev_put.part.0+0x3d/0x40 [ 26.554313] __fput+0x7bc/0xa70 [ 26.554322] fput_close_sync+0xd8/0x190 [ 26.554328] ? __pfx_fput_close_sync+0x10/0x10 [ 26.554337] __x64_sys_close+0x79/0xd0 [ 26.554344] do_syscall_64+0x117/0x6b0 [ 26.554351] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 26.554358] RIP: 0033:0x7f938c067727 [ 26.554364] Code: 48 89 fa 4c 89 df e8 28 ad 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5bf [ 26.554369] RSP: 002b:00007fff49f05980 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 [ 26.554376] RAX: ffffffffffffffda RBX: 00007f938bfd7780 RCX: 00007f938c067727 [ 26.554380] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 [ 26.554383] RBP: 00007fff49f05a10 R08: 0000000000000000 R09: 0000000000000000 [ 26.554386] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 26.554389] R13: 00007fff49f05b40 R14: 00007f938c207000 R15: 000055c148471d78 [ 26.554397] </TASK> [ 26.554399] [ 26.575612] Allocated by task 100: [ 26.575871] kasan_save_stack+0x24/0x50 [ 26.576157] kasan_save_track+0x14/0x30 [ 26.576418] __kasan_kmalloc+0x7f/0x90 [ 26.576668] __kmalloc_noprof+0x281/0x6c0 [ 26.576938] nvme_alloc_ns+0x7f7/0x3170 [ 26.577206] nvme_scan_ns+0x508/0x880 [ 26.577449] async_run_entry_fn+0x8c/0x350 [ 26.577723] process_scheduled_works+0xb6f/0x1a00 [ 26.578034] worker_thread+0x4ad/0xb40 [ 26.578283] kthread+0x34f/0x450 [ 26.578501] ret_from_fork+0x563/0x800 [ 26.578752] ret_from_fork_asm+0x1a/0x30 [ 26.579012] [ 26.579124] Freed by task 237: [ 26.579335] kasan_save_stack+0x24/0x50 [ 26.579596] kasan_save_track+0x14/0x30 [ 26.579855] kasan_save_free_info+0x3a/0x60 [ 26.580131] __kasan_slab_free+0x43/0x70 [ 26.580388] kfree+0x321/0x500 [ 26.580591] nvme_ns_head_chr_release+0x39/0x50 [ 26.580883] __fput+0x352/0xa70 [ 26.581095] fput_close_sync+0xd8/0x190 [ 26.581350] __x64_sys_close+0x79/0xd0 [ 26.581595] do_syscall_64+0x117/0x6b0 [ 26.581842] entry_SYSCAL ---truncated---
Title nvme: fix cdev lifetime
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-26T06:55:52.556Z

Reserved: 2026-09-25T10:25:14.371Z

Link: CVE-2026-98815

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:17:35.640

Modified: 2026-10-26T07:17:11.483

Link: CVE-2026-98815

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-18T00:00:00Z

Links: CVE-2026-98815 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-24T05:00:19Z

Weaknesses
  • CWE-825

    Expired Pointer Dereference