{"id":"CVE-2026-89795","state":"PUBLISHED","title":"PCI: Allow per function PCI slots to fix slot reset on s390","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: Allow per function PCI slots to fix slot reset on s390\n\nOn s390 systems, which use a machine level hypervisor, PCI devices are\nalways accessed through a form of PCI pass-through which fundamentally\noperates on a per PCI function granularity. This is also reflected in the\ns390 PCI hotplug driver which creates hotplug slots for individual PCI\nfunctions. Its reset_slot() function, which is a wrapper for\nzpci_hot_reset_device(), thus also resets individual functions.\n\nCurrently, the pci_create_slot() assigns the same pci_slot object to\nmultifunction devices. This approach worked fine on s390 systems that only\nexposed virtual functions as individual PCI domains to the operating\nsystem.  Since commit 44510d6fa0c0 (\"s390/pci: Handling multifunctions\")\ns390 supports exposing the topology of multifunction PCI devices by\ngrouping them in a shared PCI domain. This creates a problem when resetting\na function through the hotplug driver's slot_reset() interface.\n\nWhen attempting to reset a function through the hotplug driver, the shared\nslot assignment causes the wrong function to be reset instead of the\nintended one. It also leaks memory as we do create a pci_slot object for\nthe function, but don't correctly free it in pci_slot_release().\n\nAdd a flag for struct pci_slot to allow per function PCI slots for\nfunctions managed through a hypervisor, which exposes individual PCI\nfunctions while retaining the topology. Since we can use all 8 bits for\nslot 'number' (for ARI devices), change slot 'number' u16 to account for\nspecial values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES.","publishedAt":"2026-09-16T10:30:26.529Z","updatedAt":"2026-10-30T12:33:03.457Z","severity":{"score":8.4,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"afdd497ca3836eda13530ab75b416d52f6d6129a","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"b4a80e9e639cf09ef5c66b7f262c9cb5ab37bdde","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"0d1a7d67f45645106578d65181e4e492dd20ed79","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"2050d900f9adbd6d6f38d30e182bcd9ad3108467","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"ecdcceed4d377b02d4ea036b65f83f962c38ede7","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"dcc5bec09e23bbc4f9de055a11fce9937244f2c8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/pci/pci.c","drivers/pci/slot.c","include/linux/pci.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/pci/pci.c","drivers/pci/slot.c","include/linux/pci.h"]}],"references":["https://git.kernel.org/stable/c/afdd497ca3836eda13530ab75b416d52f6d6129a","https://git.kernel.org/stable/c/b4a80e9e639cf09ef5c66b7f262c9cb5ab37bdde","https://git.kernel.org/stable/c/0d1a7d67f45645106578d65181e4e492dd20ed79","https://git.kernel.org/stable/c/2050d900f9adbd6d6f38d30e182bcd9ad3108467","https://git.kernel.org/stable/c/ecdcceed4d377b02d4ea036b65f83f962c38ede7","https://git.kernel.org/stable/c/dcc5bec09e23bbc4f9de055a11fce9937244f2c8"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89795.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89795","state":"PUBLISHED","datePublished":"2026-09-16T10:30:26.529Z","dateUpdated":"2026-10-30T12:33:03.457Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.767Z"},"containers":{"cna":{"title":"PCI: Allow per function PCI slots to fix slot reset on s390","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: Allow per function PCI slots to fix slot reset on s390\n\nOn s390 systems, which use a machine level hypervisor, PCI devices are\nalways accessed through a form of PCI pass-through which fundamentally\noperates on a per PCI function granularity. This is also reflected in the\ns390 PCI hotplug driver which creates hotplug slots for individual PCI\nfunctions. Its reset_slot() function, which is a wrapper for\nzpci_hot_reset_device(), thus also resets individual functions.\n\nCurrently, the pci_create_slot() assigns the same pci_slot object to\nmultifunction devices. This approach worked fine on s390 systems that only\nexposed virtual functions as individual PCI domains to the operating\nsystem.  Since commit 44510d6fa0c0 (\"s390/pci: Handling multifunctions\")\ns390 supports exposing the topology of multifunction PCI devices by\ngrouping them in a shared PCI domain. This creates a problem when resetting\na function through the hotplug driver's slot_reset() interface.\n\nWhen attempting to reset a function through the hotplug driver, the shared\nslot assignment causes the wrong function to be reset instead of the\nintended one. It also leaks memory as we do create a pci_slot object for\nthe function, but don't correctly free it in pci_slot_release().\n\nAdd a flag for struct pci_slot to allow per function PCI slots for\nfunctions managed through a hypervisor, which exposes individual PCI\nfunctions while retaining the topology. Since we can use all 8 bits for\nslot 'number' (for ARI devices), change slot 'number' u16 to account for\nspecial values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"afdd497ca3836eda13530ab75b416d52f6d6129a","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"b4a80e9e639cf09ef5c66b7f262c9cb5ab37bdde","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"0d1a7d67f45645106578d65181e4e492dd20ed79","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"2050d900f9adbd6d6f38d30e182bcd9ad3108467","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"ecdcceed4d377b02d4ea036b65f83f962c38ede7","versionType":"git"},{"version":"44510d6fa0c00aa90b80075caa6b313b25927475","status":"affected","lessThan":"dcc5bec09e23bbc4f9de055a11fce9937244f2c8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/pci/pci.c","drivers/pci/slot.c","include/linux/pci.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/pci/pci.c","drivers/pci/slot.c","include/linux/pci.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/afdd497ca3836eda13530ab75b416d52f6d6129a"},{"url":"https://git.kernel.org/stable/c/b4a80e9e639cf09ef5c66b7f262c9cb5ab37bdde"},{"url":"https://git.kernel.org/stable/c/0d1a7d67f45645106578d65181e4e492dd20ed79"},{"url":"https://git.kernel.org/stable/c/2050d900f9adbd6d6f38d30e182bcd9ad3108467"},{"url":"https://git.kernel.org/stable/c/ecdcceed4d377b02d4ea036b65f83f962c38ede7"},{"url":"https://git.kernel.org/stable/c/dcc5bec09e23bbc4f9de055a11fce9937244f2c8"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The flaw is reached from local PCI reset paths (sysfs device reset, VFIO_DEVICE_RESET, and vfio_pci_core_enable()) that call pci_try_reset_function() -> pci_dev_reset_slot_function() -> s390 reset_slot()/zpci_hot_reset_device(); there is no network or adjacent-radio path.\nAC:L - On s390 multifunction domains pci_create_slot() matches PCI_SLOT(devfn) against a full 8-bit slot number, so siblings/VFs are assigned the wrong pci_slot and a reset deterministically invokes the other function's hotplug reset_slot() with no race or attacker-uncontrollable layout.\nPR:L - vfio_pci_core_enable() and VFIO_DEVICE_RESET call pci_try_reset_function() with no capable() check on the IOMMU path; IBM Z/LinuxONE SR-IOV VF passthrough routinely grants that VFIO fd to an unprivileged qemu/tenant user rather than init-namespace root.\nUI:N - The attacker opens the assigned VFIO device or issues VFIO_DEVICE_RESET themselves; prior admin binding of the zPCI function to vfio-pci is deployment configuration, not victim interaction.\nS:C - Function reset uses the wrongly shared pci_slot and issues zpci_hot_reset_device() on a sibling/PF outside the caller's VFIO device set, bypassing VFIO's slot-wide membership check and crossing zPCI per-function isolation into host or other-tenant devices.\nC:N - This is a wrong-function hardware reset plus a pci_slot lifetime leak; it does not perform an out-of-bounds read, use-after-free, or other disclosure of kernel or other users' memory.\nI:H - zpci_hot_reset_device() disable/re-enable of the unintended function wipes that function's hardware state behind its owner's driver, destroying in-flight I/O and device configuration on a host PF or another tenant's NIC/storage function.\nA:H - Surprise reset of an in-use PF or sibling denies that device and all VFs behind it, and can oops the bound host driver which continues MMIO against a freshly reset zPCI function, causing host kernel availability loss."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:33:03.457Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}