{"id":"CVE-2026-89507","revision":"707a977ec66145499002ceaa6e5aec67","records":[{"revision":"707a977ec66145499002ceaa6e5aec67","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89507","aliases":[],"title":"RDMA/ucma: Lock the handler in ucma_write_cm_event()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/ucma: Lock the handler in ucma_write_cm_event()\n\nctx->file may only be changed under the handler lock and the xa_lock, which\nis what stops uevents being queued for a ctx while ucma_migrate_id() moves\nit to another file.  The CM core takes that lock before invoking\nucma_event_handler(), but the write() paths that queue uevents themselves\ndo not.\n\nucma_write_cm_event() re-reads ctx->file for each of its four dereferences,\nso ucma_migrate_id() can swap it mid-sequence:\n\n\tmutex_lock(&ctx->file->mut);\t\t\t/* file A */\n\tlist_add_tail(&uevent->list, &ctx->file->event_list);\t/* file B */\n\tmutex_unlock(&ctx->file->mut);\t\t\t/* file B */\n\twake_up_interruptible(&ctx->file->poll_wait);\t/* file B */\n\nThe window is the mutex_lock() itself: the writer sleeps in it while the\nmigration reassigns ctx->file.  The list_add_tail() then runs on file B's\nevent_list holding only file A's mutex:\n\n  list_add corruption. prev->next should be next (ffff888101320f30),\n    but was ffff88814a08c418. (prev=ffff88814a075c18).\n  kernel BUG at lib/list_debug.c:32!\n  Call Trace:\n   ucma_write_cm_event+0x36e/0x5e0\n\nand file A's mut is left held forever, wedging its next writer in D state.\nThe uevent is also stranded on a list ucma_cleanup_ctx_events() will not\nwalk, so it outlives its context.  /dev/infiniband/rdma_cm is 0666 and no\nRDMA device is involved, so an unprivileged user reaches all of this.\n\nTake the handler lock, as ucma_cleanup_mc_events() does; ctx->cm_id is\npinned by the ucma_get_ctx() reference.","state":0,"publishedAt":"2026-09-11T19:43:54.013+00:00","modifiedAt":"2026-10-19T08:47:58.674+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/infiniband/core/ucma.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5\",\n                            \"lessThan\": \"4f8bb11dd2ff365e7cff1c9964ab4607292d364e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5\",\n                            \"lessThan\": \"0be1955040a2eceed0ecfc387fdc92305411d273\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5\",\n                            \"lessThan\": \"f4cc21c6a8e9d392871477f9fd98d68e5ad80272\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/infiniband/core/ucma.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.18\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.18\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.50\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.4\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/4f8bb11dd2ff365e7cff1c9964ab4607292d364e","https://git.kernel.org/stable/c/0be1955040a2eceed0ecfc387fdc92305411d273","https://git.kernel.org/stable/c/f4cc21c6a8e9d392871477f9fd98d68e5ad80272"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89507","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89507","identifiers":["CVE-2026-89507"]},"retained":false,"historicalAffected":[]}],"coverage":[]}