{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89777","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.765Z","datePublished":"2026-09-16T08:48:17.754Z","dateUpdated":"2026-09-16T14:38:28.611Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-16T14:38:28.611Z"},"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"}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","value":"AV:L - The UAF is reached only via local VFIO char-device operations: open of /dev/vfio/$GROUP or /dev/vfio/devices/vfioN, then pread/pwrite of the PCI config region through vfio_pci_core_read/write into vfio_pci_config_rw_single(). There is no network or packet path into vfio_msi_cap_len().\nAC:L - After any failed vfio_config_init() plants the dangling vdev->msi_perm, the attacker retries GET_DEVICE_FD/BIND_IOMMUFD on the same persistent vdev and deterministically calls the freed perm->readfn/writefn via MSI config accesses. The attacker controls that open/read sequence; no victim race or uncontrolled layout is required.\nPR:L - vfio_pci_core_enable() and vfio_pci_config_rw() have no capable() check on the normal IOMMU path (CAP_SYS_RAWIO is only for noiommu). Access is gated by /dev/vfio node permissions, which libvirt, kubevirt, and cloud GPU/NIC passthrough routinely grant to an unprivileged qemu user or tenant.\nUI:N - The attacker performs the VFIO open, retry, and MSI config-space pread/pwrite themselves. Prior admin binding of the PCI device to vfio-pci is deployment configuration, not victim interaction during exploitation.\nS:C - struct vfio_pci_core_device persists across open/close, so a failed open can leave a dangling msi_perm that a later tenant VM reuses. QEMU services guest PCI config cycles with VFIO pread/pwrite, so a passthrough guest can invoke the freed host function pointers and cross the VFIO/IOMMU guest-to-host boundary.\nC:H - The next successful open reuses the freed perm_bits and MSI config reads call perm->readfn on that object. Reclaiming the slab slot yields an arbitrary kernel-read primitive, which CVSS kernel guidance scores High for use-after-free.\nI:H - MSI config writes call the freed perm->writefn, and a later close double-frees the same object in vfio_config_free(). That UAF/double-free of a structure with function pointers is exploitable for arbitrary kernel write and control-flow hijack.\nA:H - The report shows a KASAN slab-use-after-free in vfio_pci_config_rw_single() followed by a general-protection fault in kfree() during vfio_config_free() that panics the host, so availability impact is a kernel oops/panic."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/vfio/pci/vfio_pci_config.c"],"versions":[{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"eb84cd81040e58dd05ac190f561f2115e3367249","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"f0eea8f9013676b42289ec35941e848b8a543e19","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"d665a1688af7f8fefd7c0eb04f2a37122ce007f4","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"25cdd2a492d868cff1e519a60fe282909c52d385","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"812f1db7f0755a19ef16ecdc5cec51bcabc5eda5","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"533d0c5feef85ee6404b9f41d5564fac6971a008","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"fda8fb7e8179561693a786a7af593f6b944a21c1","status":"affected","versionType":"git"},{"version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","lessThan":"dc77acfeb979dded39b247b60fef0399536bfa77","status":"affected","versionType":"git"},{"version":"ac370e3d1f3b01519d2705cd5815d1c9d0a8812b","status":"affected","versionType":"git"},{"version":"be363e27ec3c3a99793da2be6c07eafb95709c6b","status":"affected","versionType":"git"},{"version":"f1b10ba5739440ca51d66f0b2949cead88d2dd02","status":"affected","versionType":"git"},{"version":"dde3433de9a067a33d67d65b9093cad3e043e49e","status":"affected","versionType":"git"},{"version":"4.4.203","lessThan":"4.5","status":"affected","versionType":"semver"},{"version":"4.9.203","lessThan":"4.10","status":"affected","versionType":"semver"},{"version":"4.14.155","lessThan":"4.15","status":"affected","versionType":"semver"},{"version":"4.19.85","lessThan":"4.20","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/vfio/pci/vfio_pci_config.c"],"versions":[{"version":"4.20","status":"affected"},{"version":"0","lessThan":"4.20","status":"unaffected","versionType":"semver"},{"version":"5.10.270","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.221","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.110","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.52","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.6","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"7.3-rc1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.155"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.85"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/eb84cd81040e58dd05ac190f561f2115e3367249"},{"url":"https://git.kernel.org/stable/c/f0eea8f9013676b42289ec35941e848b8a543e19"},{"url":"https://git.kernel.org/stable/c/d665a1688af7f8fefd7c0eb04f2a37122ce007f4"},{"url":"https://git.kernel.org/stable/c/25cdd2a492d868cff1e519a60fe282909c52d385"},{"url":"https://git.kernel.org/stable/c/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5"},{"url":"https://git.kernel.org/stable/c/533d0c5feef85ee6404b9f41d5564fac6971a008"},{"url":"https://git.kernel.org/stable/c/fda8fb7e8179561693a786a7af593f6b944a21c1"},{"url":"https://git.kernel.org/stable/c/dc77acfeb979dded39b247b60fef0399536bfa77"}],"title":"vfio/pci: clear vdev->msi_perm after freeing it on init failure","x_generator":{"engine":"bippy-1.2.0"}}}}