{"id":"AZL-100088","summary":"CVE-2026-89508 affecting package kernel 6.6.150.1-1","details":"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-\u003efile stable while a uevent\nis queued.  The handler re-reads ctx-\u003efile for every dereference:\n\n\tmutex_lock(&ctx-\u003efile-\u003emut);\t\t\t/* file A */\n\tlist_add_tail(&uevent-\u003elist, &ctx-\u003efile-\u003eevent_list);\t/* file B */\n\tmutex_unlock(&ctx-\u003efile-\u003emut);\t\t\t/* file B */\n\twake_up_interruptible(&ctx-\u003efile-\u003epoll_wait);\t/* file B */\n\nA concurrent ucma_migrate_id() reassigns ctx-\u003efile 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.","modified":"2026-09-14T05:26:59Z","published":"2026-09-11T20:19:33Z","upstream":["CVE-2026-89508"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89508"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-100088.json"}}],"schema_version":"1.9.0"}