GHSA-X2M3-GXMV-QW6J

Vulnerability from github – Published: 2026-10-18 18:32 – Updated: 2026-10-18 18:32
VLAI
Details

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] [ 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] [ 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---

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-98815"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:35Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvme: fix cdev lifetime\n\nSashiko bot reported a potential problem for the cdev lifetime in [0]\n- the code there is heavily based on the NVMe code.\n\nCurrently the NS head .open and .release file_operations methods take and\nput a reference to the nvme_ns_head to ensure that this structure does not\ndisappear while we open fds for that cdev.\n\nIn multipath mode, when we teardown the NS head, we call nvme_cdev_del() -\u003e\ncdev_device_del() -\u003e cdev_del(). However after cdev_del() returns, cdevs\nalready open will remain and their fops will still be callable. As such,\nwe can still reference the cdev after the nvme_ns_head reference count\ndrops to 0 (and is freed).\n\nThis can be shown with an application which delays between opening the cdev\nand issuing the ioctl while the NS head is being torn down:\n\n# ./ioctl_file /dev/ng1n1 \u0026\n# waiting 10 seconds ....\n\n# ./ini_nvme_teardown.sh\n[   21.221718] nvme nvme1: Removing ctrl: NQN \"nvme-test-target\"\n[   21.274609] nvme nvme2: Removing ctrl: NQN \"nvme-test-target\"\n# now going to issue ioctl ....\n[   26.549285] ==================================================================\n[   26.550841] BUG: KASAN: slab-use-after-free in cdev_put.part.0+0x3d/0x40\n[   26.552352] Read of size 8 at addr ffff88811e7fa170 by task ioctl_file/237\n[   26.553805]\n[   26.554227] CPU: 3 UID: 0 PID: 237 Comm: ioctl_file Not tainted 7.2.0-rc1-00004-g6852a10e32d4 #921 PREEMPT(lazy)\n[   26.554236] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[   26.554241] Call Trace:\n[   26.554245]  \u003cTASK\u003e\n[   26.554248]  dump_stack_lvl+0x68/0xa0\n[   26.554266]  print_report+0x10d/0x5d0\n[   26.554276]  ? __virt_addr_valid+0x21d/0x3f0\n[   26.554287]  ? cdev_put.part.0+0x3d/0x40\n[   26.554292]  kasan_report+0x96/0xd0\n[   26.554300]  ? cdev_put.part.0+0x3d/0x40\n[   26.554307]  cdev_put.part.0+0x3d/0x40\n[   26.554313]  __fput+0x7bc/0xa70\n[   26.554322]  fput_close_sync+0xd8/0x190\n[   26.554328]  ? __pfx_fput_close_sync+0x10/0x10\n[   26.554337]  __x64_sys_close+0x79/0xd0\n[   26.554344]  do_syscall_64+0x117/0x6b0\n[   26.554351]  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n[   26.554358] RIP: 0033:0x7f938c067727\n[   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 \u003c5bf\n[   26.554369] RSP: 002b:00007fff49f05980 EFLAGS: 00000202 ORIG_RAX: 0000000000000003\n[   26.554376] RAX: ffffffffffffffda RBX: 00007f938bfd7780 RCX: 00007f938c067727\n[   26.554380] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003\n[   26.554383] RBP: 00007fff49f05a10 R08: 0000000000000000 R09: 0000000000000000\n[   26.554386] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000\n[   26.554389] R13: 00007fff49f05b40 R14: 00007f938c207000 R15: 000055c148471d78\n[   26.554397]  \u003c/TASK\u003e\n[   26.554399]\n[   26.575612] Allocated by task 100:\n[   26.575871]  kasan_save_stack+0x24/0x50\n[   26.576157]  kasan_save_track+0x14/0x30\n[   26.576418]  __kasan_kmalloc+0x7f/0x90\n[   26.576668]  __kmalloc_noprof+0x281/0x6c0\n[   26.576938]  nvme_alloc_ns+0x7f7/0x3170\n[   26.577206]  nvme_scan_ns+0x508/0x880\n[   26.577449]  async_run_entry_fn+0x8c/0x350\n[   26.577723]  process_scheduled_works+0xb6f/0x1a00\n[   26.578034]  worker_thread+0x4ad/0xb40\n[   26.578283]  kthread+0x34f/0x450\n[   26.578501]  ret_from_fork+0x563/0x800\n[   26.578752]  ret_from_fork_asm+0x1a/0x30\n[   26.579012]\n[   26.579124] Freed by task 237:\n[   26.579335]  kasan_save_stack+0x24/0x50\n[   26.579596]  kasan_save_track+0x14/0x30\n[   26.579855]  kasan_save_free_info+0x3a/0x60\n[   26.580131]  __kasan_slab_free+0x43/0x70\n[   26.580388]  kfree+0x321/0x500\n[   26.580591]  nvme_ns_head_chr_release+0x39/0x50\n[   26.580883]  __fput+0x352/0xa70\n[   26.581095]  fput_close_sync+0xd8/0x190\n[   26.581350]  __x64_sys_close+0x79/0xd0\n[   26.581595]  do_syscall_64+0x117/0x6b0\n[   26.581842]  entry_SYSCAL\n---truncated---",
  "id": "GHSA-x2m3-gxmv-qw6j",
  "modified": "2026-10-18T18:32:04Z",
  "published": "2026-10-18T18:32:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98815"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/98b09ad7934482e64db4b4477d91e3bbf43adf4c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9952f3882ecba709092379b71e02b09762b26f96"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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