{"cve":"CVE-2026-89508","nvd":{"published":"2026-09-11T20:19:33.143","modified":"2026-10-19T09:17:45.060","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/ucma: Lock the handler in ucma_set_ib_path()\n\nucma_set_ib_path() calls ucma_event_handler() straight from the write()\npath, without the handler lock that keeps ctx->file stable while a uevent\nis queued.  The handler re-reads ctx->file for every dereference:\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\nA concurrent ucma_migrate_id() reassigns ctx->file while the SET_OPTION\ncaller sleeps in mutex_lock(), so the list_add_tail() lands on file B's\nevent_list while only file A's mutex is held, racing every other user of\nthat list:\n\n  BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x1aa/0x1c0\n  Read of size 8 at addr ffff888153c6a418 by task poc_corr/486\n  Call Trace:\n   __list_add_valid_or_report+0x1aa/0x1c0\n   ucma_event_handler+0x1be/0xc00\n   ucma_set_ib_path+0x45e/0x710\n   ucma_set_option+0x32e/0x590\n   ucma_write+0x1f9/0x330\n  Allocated by task 505:\n   ucma_write_cm_event+0x1a1/0x660\n  Freed by task 505:\n   kfree+0x1da/0x4c0\n   ucma_get_event+0x5d5/0x7e0\n\nThe freed object is a ucma_event that another thread dequeued from file B's\nlist under file B's mutex.  File A's mut is left held on top of that,\nwedging its next writer in uninterruptible sleep.\n\nThis path needs a bound and address-resolved cm_id, so it requires an RDMA\ndevice to be present.\n\nTake the handler lock around the call.","cvss_v4":null,"cvss_v3":{"version":"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},"cwes":[],"references":["https://git.kernel.org/stable/c/28ac2dd416482d1c763c4af5d61af465b387fb50","https://git.kernel.org/stable/c/3dd07b369371a2f29e1c3caf1ade85bb92b4c551","https://git.kernel.org/stable/c/43a7d8ae9f645dc00235cfa4bf57673c20b769f8","https://git.kernel.org/stable/c/71dc206f2e2a645dac78879768762451aa1799f7","https://git.kernel.org/stable/c/764586f8f6180084c5a7d622120f526acc6ce0c9"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-89508","score":0.00126,"percentile":0.0224,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}