CVE-2026-80824 (GCVE-0-2026-80824)
Vulnerability from cvelistv5
Published
2026-09-04 15:54
Modified
2026-09-04 15:54
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: usbfs: fix use-after-free of usb_device in usbdev_release() usbdev_release() drops its reference to the struct usb_device before draining the list of completed async URBs, but that drain path reads back through the same object: free_async() calls dec_usb_memory_use_count() for any URB whose buffer came from the usbfs mmap() region, and its first statement is bus_to_hcd(ps->dev->bus). After a disconnect the usbfs reference can be the last one, in which case usb_put_dev() frees the device and the subsequent loop reads offset 80 of freed memory and uses the result as a struct usb_hcd *, which hcd_buffer_free_pages() then dereferences. This is reachable by an unprivileged process that has read/write access to a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the mapping, wait for the device to be unplugged, then munmap() and close(). It reproduces on every attempt rather than being a race, because a live MAP_SHARED vma holds a reference on the struct file, so usbdev_release() cannot run until the last vma is gone and the freeing branch of dec_usb_memory_use_count() is always taken. BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410 Read of size 8 at addr ffff8880122ee050 by task poc/769 CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G B 6.12.94 #3 Call Trace: dec_usb_memory_use_count+0x3ae/0x410 free_async+0x2aa/0x4f0 usbdev_release+0x375/0x460 __fput+0x3ea/0xb50 __x64_sys_close+0x86/0x100 Allocated by task 11: usb_alloc_dev+0x55/0xd90 hub_event+0x2524/0x43d0 Freed by task 769: kfree+0x121/0x360 device_release+0xd2/0x280 usb_put_dev+0x23/0x30 usbdev_release+0x2d8/0x460 Release the device reference after the drain loop instead. Nothing between the two points requires it to have been dropped.
References
Impacted products
Vendor Product Version
Linux Linux Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
Version: f7d34b445abc00e979b7cf36b9580ac3d1a47cd8
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
            "drivers/usb/core/devio.c"
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          "vendor": "Linux",
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              "version": "0",
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              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
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      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: usbfs: fix use-after-free of usb_device in usbdev_release()\n\nusbdev_release() drops its reference to the struct usb_device before\ndraining the list of completed async URBs, but that drain path reads back\nthrough the same object: free_async() calls dec_usb_memory_use_count()\nfor any URB whose buffer came from the usbfs mmap() region, and its first\nstatement is bus_to_hcd(ps-\u003edev-\u003ebus).\n\nAfter a disconnect the usbfs reference can be the last one, in which case\nusb_put_dev() frees the device and the subsequent loop reads offset 80 of\nfreed memory and uses the result as a struct usb_hcd *, which\nhcd_buffer_free_pages() then dereferences.\n\nThis is reachable by an unprivileged process that has read/write access to\na /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the\nmapping, wait for the device to be unplugged, then munmap() and close().\nIt reproduces on every attempt rather than being a race, because a live\nMAP_SHARED vma holds a reference on the struct file, so usbdev_release()\ncannot run until the last vma is gone and the freeing branch of\ndec_usb_memory_use_count() is always taken.\n\n  BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410\n  Read of size 8 at addr ffff8880122ee050 by task poc/769\n  CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G    B    6.12.94 #3\n\n  Call Trace:\n   dec_usb_memory_use_count+0x3ae/0x410\n   free_async+0x2aa/0x4f0\n   usbdev_release+0x375/0x460\n   __fput+0x3ea/0xb50\n   __x64_sys_close+0x86/0x100\n\n  Allocated by task 11:\n   usb_alloc_dev+0x55/0xd90\n   hub_event+0x2524/0x43d0\n\n  Freed by task 769:\n   kfree+0x121/0x360\n   device_release+0xd2/0x280\n   usb_put_dev+0x23/0x30\n   usbdev_release+0x2d8/0x460\n\nRelease the device reference after the drain loop instead. Nothing between\nthe two points requires it to have been dropped."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T15:54:28.038Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0a960b88c5979f853019d4dc4957dfbeeb193440"
        },
        {
          "url": "https://git.kernel.org/stable/c/96f5520fc9a5e4bbf77ac93c9d5ce502f597e6cf"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd4bffc621a8cb2f4d9ed9b6447415de524a3bef"
        },
        {
          "url": "https://git.kernel.org/stable/c/65879e0a452ca2a234b9475e0c11aff7a4343738"
        },
        {
          "url": "https://git.kernel.org/stable/c/b3cde26a66b04f1d90ed0b675899c88b4e49d424"
        },
        {
          "url": "https://git.kernel.org/stable/c/5f08c45bdcfd28d1171de38c5ef29fc89a76eedc"
        },
        {
          "url": "https://git.kernel.org/stable/c/7f0278e474c4d1c4457974ff1137cc385c944ab3"
        },
        {
          "url": "https://git.kernel.org/stable/c/47a7f98fbb5006d46d15a3a210ffdc61448a4f19"
        },
        {
          "url": "https://git.kernel.org/stable/c/0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671"
        }
      ],
      "title": "usb: usbfs: fix use-after-free of usb_device in usbdev_release()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80824",
    "datePublished": "2026-09-04T15:54:28.038Z",
    "dateReserved": "2026-08-26T14:34:25.795Z",
    "dateUpdated": "2026-09-04T15:54:28.038Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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