{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89748", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.762Z", "datePublished": "2026-09-11T19:46:53.070Z", "dateUpdated": "2026-10-19T08:52:02.172Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:52:02.172Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix retry exhaustion in simple ring buffer reader swap\n\nsimple_ring_buffer_swap_reader_page() starts with retry set to 8 and\npost-decrements it only after a failed link replacement. On the final\nattempt, a successful replacement leaves retry at zero, while a failed\nreplacement leaves it at -1.\n\nThe current !retry test reverses both outcomes. It returns an error after\na successful final replacement, leaving the link update complete but the\nreader bookkeeping unfinished. After a failed final replacement, it\nfalls through and updates the head and reader pointers as though the\nreplacement succeeded, which can corrupt the ring.\n\nTreat only a negative counter as exhaustion and return the documented\n-EBUSY error." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Reached only via local tracefs reads of remotes/*/trace_pipe or remotes/*/trace, which call ring_buffer_consume/peek -> __rb_get_reader_page_from_remote() -> swap_reader_page() into simple_ring_buffer_swap_reader_page() (ARM64 nVHE hyp tracing or the TRACE_REMOTE_TEST module). No network, adjacent-radio, or physical path exists.\nAC:L - An attacker with tracefs access shrinks remotes/*/buffer_size_kb, enables tracing, and storms events via remotes/*/write_event or KVM hyp events while reading trace_pipe. That drives the writer to move the head across the eight cmpxchg retries; the attacker controls both sides and can retry until inverted exhaustion hits.\nPR:L - remotes/ files are mode 0440/0640 and use custom fops with no capable() or tracing_check_open_get_tr() check, only DAC. tracing-gid mounts on Android eng/Perfetto, ChromeOS, and developer kernels grant this to unprivileged tracing-group users, matching CVE-2026-89499 and prior CNA tracefs scores.\nUI:N - The attacker opens, configures, and reads their own remotes/*/trace_pipe and related tracefs files. No separate victim mount, click, or other user action is required.\nS:U - Corruption is of host kernel ring-buffer buffer_page lists and simple_ring_buffer metadata in the same OS security authority. A host-local tracefs user cannot use this as a VM, IOMMU, or guest-to-host escape.\nC:H - Inverted retry exhaustion leaves the reader page in the writer ring (success reported as error) or makes the host adopt a live writer page as reader (failure reported as success). Concurrent commits tear event headers so rb_event_length() returns unbounded sizes, and later peeks follow corrupted buffer_page pointers, enabling out-of-bounds kernel reads.\nI:H - After a failed final cmpxchg the function still updates head_page, reader_page, link.prev, and meta.reader.id, and the host splices buffer_page lists as if the swap succeeded. That kernel list-metadata corruption is exploitable for arbitrary writes and control-flow hijack, matching sibling remote-swap CVE-2026-89499.\nA:H - The inverted path hits WARN_ON_ONCE(prev_reader == new_reader) on the host, can infinite-spin in simple_rb_find_head() on SIMPLE_RB_LINK_HEAD_MOVING, and oopses on corrupted page pointers. panic_on_warn turns those WARNs into panics, and the attacker can retrigger the path at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/simple_ring_buffer.c" ], "versions": [ { "version": "34e5b958bdad0f9cf16306368bbc2dc5b2a50143", "lessThan": "df02489aa3aa1834659f0d20c89f7d212047d268", "status": "affected", "versionType": "git" }, { "version": "34e5b958bdad0f9cf16306368bbc2dc5b2a50143", "lessThan": "e0d3aed7b12cf37b74c7cc5265073d0263b49cde", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/simple_ring_buffer.c" ], "versions": [ { "version": "7.1", "status": "affected" }, { "version": "0", "lessThan": "7.1", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "7.1", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/df02489aa3aa1834659f0d20c89f7d212047d268" }, { "url": "https://git.kernel.org/stable/c/e0d3aed7b12cf37b74c7cc5265073d0263b49cde" } ], "title": "tracing: Fix retry exhaustion in simple ring buffer reader swap", "x_generator": { "engine": "bippy-1.2.0" } } } }