{"id":"CVE-2026-80548","state":"PUBLISHED","title":"s390/vfio_ccw: Selectively expand io_mutex","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Selectively expand io_mutex\n\nThe io_mutex was defined to serialize the io_regions, but then has\nalso sort of been associated with the I/O themselves because of\nthe close relationship they share.\n\nWith the handful of races that are possible, the choices are either to:\n A) expand the scope of io_mutex to close these remaining windows, or\n B) reduce the scope of io_mutex to just io_region, and introduce a new\n    lock mechanism for the remaining I/O resources\n\nThis patch implements A, since B brings with it a lot more interactions\nthat would need to be tracked and kept in a correct hierarchy. It also\ntakes advantage of the workqueue element for cp_free() that now gets\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\ncontext and thus cannot acquire a mutex itself.","publishedAt":"2026-08-26T14:37:18.759Z","updatedAt":"2026-10-16T19:26:25.857Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"56d7488533ceac4e986e96e15c9e487a2245bc01","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"f72a51810d49411bd8cad0c2df8592320a2fe5cc","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"b6aecea4b2b246f9fbd98a5712daa1193a60818e","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"2a5ac0c0f1f7da33929211a2e41911bf72ee35d8","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"34f4feff3e90bd09308fad0974e97113b23b812a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/cio/vfio_ccw_chp.c","drivers/s390/cio/vfio_ccw_cp.c","drivers/s390/cio/vfio_ccw_drv.c","drivers/s390/cio/vfio_ccw_fsm.c","drivers/s390/cio/vfio_ccw_private.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.2","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.153","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.105","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.46","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.10","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/cio/vfio_ccw_chp.c","drivers/s390/cio/vfio_ccw_cp.c","drivers/s390/cio/vfio_ccw_drv.c","drivers/s390/cio/vfio_ccw_fsm.c","drivers/s390/cio/vfio_ccw_private.h"]}],"references":["https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0","https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01","https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc","https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd","https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e","https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8","https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80548.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80548","state":"PUBLISHED","datePublished":"2026-08-26T14:37:18.759Z","dateUpdated":"2026-10-16T19:26:25.857Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.766Z"},"containers":{"cna":{"title":"s390/vfio_ccw: Selectively expand io_mutex","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Selectively expand io_mutex\n\nThe io_mutex was defined to serialize the io_regions, but then has\nalso sort of been associated with the I/O themselves because of\nthe close relationship they share.\n\nWith the handful of races that are possible, the choices are either to:\n A) expand the scope of io_mutex to close these remaining windows, or\n B) reduce the scope of io_mutex to just io_region, and introduce a new\n    lock mechanism for the remaining I/O resources\n\nThis patch implements A, since B brings with it a lot more interactions\nthat would need to be tracked and kept in a correct hierarchy. It also\ntakes advantage of the workqueue element for cp_free() that now gets\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\ncontext and thus cannot acquire a mutex itself."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"56d7488533ceac4e986e96e15c9e487a2245bc01","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"f72a51810d49411bd8cad0c2df8592320a2fe5cc","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"b6aecea4b2b246f9fbd98a5712daa1193a60818e","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"2a5ac0c0f1f7da33929211a2e41911bf72ee35d8","versionType":"git"},{"version":"4f76617378ee97c557b526cb58d3c61eb0a9c963","status":"affected","lessThan":"34f4feff3e90bd09308fad0974e97113b23b812a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/cio/vfio_ccw_chp.c","drivers/s390/cio/vfio_ccw_cp.c","drivers/s390/cio/vfio_ccw_drv.c","drivers/s390/cio/vfio_ccw_fsm.c","drivers/s390/cio/vfio_ccw_private.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.2","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.153","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.105","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.46","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.10","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/s390/cio/vfio_ccw_chp.c","drivers/s390/cio/vfio_ccw_cp.c","drivers/s390/cio/vfio_ccw_drv.c","drivers/s390/cio/vfio_ccw_fsm.c","drivers/s390/cio/vfio_ccw_private.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0"},{"url":"https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01"},{"url":"https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc"},{"url":"https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd"},{"url":"https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e"},{"url":"https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8"},{"url":"https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a"}],"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 bug is reached only through local VFIO mediated-device syscalls (read/write/ioctl on vfio-ccw device fds) and deferred work from hardware I/O interrupts and channel-path events; vfio-ccw has no network, Bluetooth, or physical-bus entry point.\nAC:L - The VFIO client controls both sides of each race window: it can submit channel I/O, close or reset the device, and trigger DMA unmap while io_work, notoper_work, or fsm_close concurrently run cp_free, cp_update_scsw, or cp_iova_pinned without full io_mutex protection, and retry to win reliably.\nPR:L - Exploitation requires an opened vfio-ccw mdev device fd (typical QEMU/libvirt VM operator or delegated /dev/vfio holder on IBM Z passthrough hosts), not init-namespace root; mdev creation is admin setup, but triggering the races needs only that delegated VFIO client access.\nUI:N - No separate victim action is required; once vfio-ccw passthrough is configured, the attacker issues concurrent channel I/O, region access, device close/reset, or DMA unmap without needing another user to mount media or interact.\nS:C - On IBM Z/LinuxONE, vfio-ccw passes DASD/CCW subchannels into KVM guests; guest-driven channel I/O and path events trigger host interrupt/workqueue activity concurrent with VFIO client teardown, corrupting hypervisor kernel memory outside the VM security boundary.\nC:H - cp_free racing with cp_update_scsw, cp_iova_pinned, and io_region access without io_mutex causes use-after-free on ccwchain_list and page_array structures; per kernel UAF guidance this enables attacker-influenced heap reuse and arbitrary kernel read primitives.\nI:H - Concurrent cp_free during cp_init, page_array_unpin_free, memcpy into io_region, and mutex operations on freed channel_program memory provides heap-sprayable arbitrary write and control-flow hijack potential beyond a simple crash.\nA:H - Use-after-free and double-free of channel program structures during concurrent I/O completion, not-operational cleanup, or device close can immediately oops or panic the host kernel from invalid list/mutex access, and successful exploitation can crash or hang the system."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-27T12:40:08.507Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"5.15.218"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.1.185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.6.153"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.12.105"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.18.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"7.1.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-80548","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:17:03.411109Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:25.857Z"}}]}}}