CVE-2026-89777
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: vfio/pci: clear vdev->msi_perm after freeing it on init failure vfio_msi_cap_len() lazily allocates the per-device MSI permission table: vdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT); if (!vdev->msi_perm) return -ENOMEM; ret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags); if (ret) { kfree(vdev->msi_perm); return ret; /* vdev->msi_perm left dangling */ } When init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the error path frees vdev->msi_perm but leaves the freed pointer stored in it. vdev->msi_perm is not re-zeroed later because struct vfio_pci_core_device is per-device and persists across open/close cycles, and the vfio_config_init() error path returns without calling vfio_config_free(). So the dangling pointer outlives the failed open. That leads to two use-after-frees on the same device: 1. Reuse. The next vfio_config_init() sees the stale pointer at "if (vdev->msi_perm) return len;" and reuses the freed object. MSI config accesses in vfio_pci_config_rw_single() then dereference and call the freed perm->readfn / perm->writefn function pointers. 2. Double free. A later vfio_config_free() runs free_perm_bits() and kfree() on the already-freed object. Fix it by NULLing vdev->msi_perm after the kfree(), matching the NULL-after-free discipline already used in free_perm_bits() and vfio_config_free(). BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961) Read of size 8 at addr ffff88800fcc88d0 by task exploit/143 Call Trace: ... kasan_report (mm/kasan/report.c:595) vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961) vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986) vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599) vfs_read (fs/read_write.c:572) __x64_sys_pread64 (fs/read_write.c:764) do_syscall_64 (arch/x86/entry/syscall_64.c:94) ... Followed on device close by a double free of the same object: Oops: general protection fault, probably for non-canonical address 0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI RIP: 0010:kfree (mm/slub.c:6711) Call Trace: vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861) vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685) vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777) vfio_df_close (drivers/vfio/vfio_main.c:602) vfio_device_fops_release (drivers/vfio/vfio_main.c:648) __fput (fs/file_table.c:512) __x64_sys_close (fs/open.c:1496) do_syscall_64 (arch/x86/entry/syscall_64.c:94) ... Kernel panic - not syncing: Fatal exception
View original CVE JSON
{
"id": "CVE-2026-89777",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-16T09:17:08.073",
"lastModified": "2026-10-19T09:18:20.933",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/pci: clear vdev->msi_perm after freeing it on init failure\n\nvfio_msi_cap_len() lazily allocates the per-device MSI permission table:\n\n\tvdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT);\n\tif (!vdev->msi_perm)\n\t\treturn -ENOMEM;\n\n\tret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags);\n\tif (ret) {\n\t\tkfree(vdev->msi_perm);\n\t\treturn ret;\t\t/* vdev->msi_perm left dangling */\n\t}\n\nWhen init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the\nerror path frees vdev->msi_perm but leaves the freed pointer stored in\nit. vdev->msi_perm is not re-zeroed later because struct\nvfio_pci_core_device is per-device and persists across open/close cycles,\nand the vfio_config_init() error path returns without calling\nvfio_config_free(). So the dangling pointer outlives the failed open.\n\nThat leads to two use-after-frees on the same device:\n\n1. Reuse. The next vfio_config_init() sees the stale pointer at\n \"if (vdev->msi_perm) return len;\" and reuses the freed object. MSI\n config accesses in vfio_pci_config_rw_single() then dereference and\n call the freed perm->readfn / perm->writefn function pointers.\n\n2. Double free. A later vfio_config_free() runs free_perm_bits() and\n kfree() on the already-freed object.\n\nFix it by NULLing vdev->msi_perm after the kfree(), matching the\nNULL-after-free discipline already used in free_perm_bits() and\nvfio_config_free().\n\n BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n Read of size 8 at addr ffff88800fcc88d0 by task exploit/143\n Call Trace:\n ...\n kasan_report (mm/kasan/report.c:595)\n vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986)\n vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599)\n vfs_read (fs/read_write.c:572)\n __x64_sys_pread64 (fs/read_write.c:764)\n do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n ...\n\nFollowed on device close by a double free of the same object:\n\n Oops: general protection fault, probably for non-canonical address\n 0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI\n RIP: 0010:kfree (mm/slub.c:6711)\n Call Trace:\n vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861)\n vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685)\n vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777)\n vfio_df_close (drivers/vfio/vfio_main.c:602)\n vfio_device_fops_release (drivers/vfio/vfio_main.c:648)\n __fput (fs/file_table.c:512)\n __x64_sys_close (fs/open.c:1496)\n do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n ...\n Kernel panic - not syncing: Fatal exception"
}
],
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{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
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"metrics": {
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{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "CHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 2.0,
"impactScore": 6.0
}
]
},
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