{"id":"AZL-108900","summary":"CVE-2026-98694 affecting package kernel 6.6.157.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: Fix KASAN reported use-after-free when request is canceled\n\nAlan reported that when doing stress testing sometimes KASAN notices\nuse-after-free during control channel operation (stripped down keeping\nthe relevant parts):\n\n BUG: KASAN: slab-use-after-free in tb_cfg_request_sync+0x240/0x250 [thunderbolt]\n Read of size 24 at addr ffff88811067f290 by task kworker/u40:2/1760\n  \u003cTASK\u003e\n  tb_cfg_request_sync+0x240/0x250 [thunderbolt]\n  tb_cfg_read_raw+0x367/0x510 [thunderbolt]\n  tb_cfg_read+0xec/0x240 [thunderbolt]\n  tb_port_get_link_generation+0x258/0x420 [thunderbolt]\n  tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]\n  tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]\n  tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]\n  tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]\n  tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]\n  process_one_work+0x675/0x1230\n  worker_thread+0x5e6/0xf70\n  kthread+0x365/0x470\n  ret_from_fork+0x54d/0x710\n  ret_from_fork_asm+0x1a/0x30\n  \u003c/TASK\u003e\n\n Allocated by task 1760:\n  __kmalloc_cache_noprof+0x1ee/0x550\n  tb_cfg_read_raw+0x1d3/0x510 [thunderbolt]\n  tb_cfg_read+0xec/0x240 [thunderbolt]\n  tb_port_get_link_generation+0x258/0x420 [thunderbolt]\n  tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]\n  tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]\n  tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]\n  tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]\n  tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]\n  process_one_work+0x675/0x1230\n  worker_thread+0x5e6/0xf70\n  kthread+0x365/0x470\n  ret_from_fork+0x54d/0x710\n  ret_from_fork_asm+0x1a/0x30\n\n Freed by task 926:\n  kfree+0x18f/0x4a0\n  tb_cfg_request_put+0xb7/0xe0 [thunderbolt]\n  tb_cfg_request_work+0x82/0x120 [thunderbolt]\n  process_one_work+0x675/0x1230\n  worker_thread+0x5e6/0xf70\n  kthread+0x365/0x470\n  ret_from_fork+0x54d/0x710\n  ret_from_fork_asm+0x1a/0x30\n\n Second to last potentially related work creation:\n  __queue_work+0x575/0xd00\n  queue_work_on+0x77/0x80\n  tb_cfg_request_cancel+0xc7/0x260 [thunderbolt]\n  tb_cfg_request_sync+0x1f6/0x250 [thunderbolt]\n  tb_cfg_read_raw+0x367/0x510 [thunderbolt]\n  tb_cfg_read+0xec/0x240 [thunderbolt]\n  tb_port_get_link_generation+0x258/0x420 [thunderbolt]\n  tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt]\n  tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt]\n  tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt]\n  tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt]\n  tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt]\n  process_one_work+0x675/0x1230\n  worker_thread+0x5e6/0xf70\n  kthread+0x365/0x470\n  ret_from_fork+0x54d/0x710\n  ret_from_fork_asm+0x1a/0x30\n\nThe last stack trace is helpful because it shows that we are cancelling\na request and looking at tb_cfg_request_cancel() what might happen is\nthat tb_cfg_request_work() completes right before tb_cfg_request_cancel()\nstarts and because of this it will call schedule_work() queueing the\nsame work to run again. However, it is already removed from the\nrequest_queue and reference count is dropped so when\ntb_cfg_request_work() triggers again it will access memory that is\nalready released.\n\nFix this so that we first make sure a cancelled request is not handed\naway from tb_cfg_request_find() or scheduled to run. Then instead of\nrelying on the worker to clean up the request we will do it in\ntb_cfg_request_cancel() after the work is canceled from running. Make\ntb_cfg_request_dequeue() release the request only if it was actually\nremoved from the queue.","modified":"2026-10-20T05:35:13Z","published":"2026-10-18T16:17:22Z","upstream":["CVE-2026-98694"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98694"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-108900.json"}}],"schema_version":"1.9.0"}