{"api_version":"1","generated_at":"2026-07-26T21:47:39+00:00","cve":"CVE-2026-64434","urls":{"html":"https://cve.report/CVE-2026-64434","api":"https://cve.report/api/cve/CVE-2026-64434.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64434","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64434"},"summary":{"title":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\n\nl2cap_chan_timeout() runs asynchronously and accesses chan->conn. If\nthe connection is torn down while the timer is running or pending,\nchan->conn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn->lock:\n\n| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83\n|\n| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)\n| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\n| Workqueue: events l2cap_chan_timeout\n| Call Trace:\n|  <TASK>\n|  instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n|  atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n|  __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n|  mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n|  l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|  </TASK>\n|\n| Allocated by task 320:\n|  l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075\n|  l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452\n|  hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]\n|  hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760\n|  hci_event_func net/bluetooth/hci_event.c:7796 [inline]\n|  hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847\n|  hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|\n| Freed by task 322:\n|  hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]\n|  hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736\n|  hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405\n|  hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]\n|  hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679\n|  vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690\n|  __fput+0x369/0x890 fs/file_table.c:510\n|  task_work_run+0x160/0x1d0 kernel/task_work.c:233\n|  get_signal+0xf5b/0x1120 kernel/signal.c:2810\n|  arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337\n|  __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]\n|  exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98\n|  do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100\n|  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n|\n| The buggy address belongs to the object at ffff8881298d9400\n|  which belongs to the cache kmalloc-512 of size 512\n| The buggy address is located 336 bytes inside of\n|  freed 512-byte region [ffff8881298d9400, ffff8881298d9600)\n\nFix it by having chan->conn hold a reference to l2cap_conn (via\nl2cap_conn_get) when the channel is added to the connection, and\nreleasing it in the channel destructor. This ensures the l2cap_conn\nremains alive as long as the channel exists.\n\nA new FLAG_DEL channel flag is introduced to indicate that the ch\n---truncated---","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:27","updated_at":"2026-07-25 10:17:27"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b","name":"https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277","name":"https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d","name":"https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189","name":"https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032","name":"https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64434","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64434","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89dec92041717b027216e110599e4f6d6c921b79 91047a4396a8b1857a6f712a90cf33ec0012b189 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 50dfec218808b148ab4247b1858031b7a32015c5 0b0e2bf39cf99e458d991b9df253727e036a7d7d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 859d3ace791ed878ae9ba5522c7844d960da8f88 d3b739db5dc6f688a60d56da872fabaf65246032 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c8e620467a7b51562dbcefbd1f09f288d7d710d 50c38d9f42a529691e4e67ea9cedf4f0bfc8d277 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c8e620467a7b51562dbcefbd1f09f288d7d710d b66774b48dd98f07254951f74ea6f513efe7ff8b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3634cbdc2eb414b69ffa752ddbe5e0458518e321 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e1c100e2d61bd8c718b7d91fe3e050780a9bf72d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7555fd885a0603f50e49a655850a1f2bd8a25398 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.143 6.6.145 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.93 6.12.97 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.35 6.18.39 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.10.259 5.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15.210 5.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.176 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0.12 7.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.1","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.39 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.4 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64434","cve":"CVE-2026-64434","epss":"0.002090000","percentile":"0.111710000","score_date":"2026-07-25","updated_at":"2026-07-26 00:12:33"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/bluetooth/l2cap.h","net/bluetooth/l2cap_core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"91047a4396a8b1857a6f712a90cf33ec0012b189","status":"affected","version":"89dec92041717b027216e110599e4f6d6c921b79","versionType":"git"},{"lessThan":"0b0e2bf39cf99e458d991b9df253727e036a7d7d","status":"affected","version":"50dfec218808b148ab4247b1858031b7a32015c5","versionType":"git"},{"lessThan":"d3b739db5dc6f688a60d56da872fabaf65246032","status":"affected","version":"859d3ace791ed878ae9ba5522c7844d960da8f88","versionType":"git"},{"lessThan":"50c38d9f42a529691e4e67ea9cedf4f0bfc8d277","status":"affected","version":"8c8e620467a7b51562dbcefbd1f09f288d7d710d","versionType":"git"},{"lessThan":"b66774b48dd98f07254951f74ea6f513efe7ff8b","status":"affected","version":"8c8e620467a7b51562dbcefbd1f09f288d7d710d","versionType":"git"},{"status":"affected","version":"3634cbdc2eb414b69ffa752ddbe5e0458518e321","versionType":"git"},{"status":"affected","version":"e1c100e2d61bd8c718b7d91fe3e050780a9bf72d","versionType":"git"},{"status":"affected","version":"deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9","versionType":"git"},{"status":"affected","version":"7555fd885a0603f50e49a655850a1f2bd8a25398","versionType":"git"},{"lessThan":"6.6.145","status":"affected","version":"6.6.143","versionType":"semver"},{"lessThan":"6.12.97","status":"affected","version":"6.12.93","versionType":"semver"},{"lessThan":"6.18.39","status":"affected","version":"6.18.35","versionType":"semver"},{"lessThan":"5.11","status":"affected","version":"5.10.259","versionType":"semver"},{"lessThan":"5.16","status":"affected","version":"5.15.210","versionType":"semver"},{"lessThan":"6.2","status":"affected","version":"6.1.176","versionType":"semver"},{"lessThan":"7.1","status":"affected","version":"7.0.12","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/bluetooth/l2cap.h","net/bluetooth/l2cap_core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.1"},{"lessThan":"7.1","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.39","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"6.6.143","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.12.93","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.39","versionStartIncluding":"6.18.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.4","versionStartIncluding":"7.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc1","versionStartIncluding":"7.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.259","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.210","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.176","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\n\nl2cap_chan_timeout() runs asynchronously and accesses chan->conn. If\nthe connection is torn down while the timer is running or pending,\nchan->conn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn->lock:\n\n| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83\n|\n| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)\n| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\n| Workqueue: events l2cap_chan_timeout\n| Call Trace:\n|  <TASK>\n|  instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n|  atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n|  __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n|  mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n|  l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|  </TASK>\n|\n| Allocated by task 320:\n|  l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075\n|  l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452\n|  hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]\n|  hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760\n|  hci_event_func net/bluetooth/hci_event.c:7796 [inline]\n|  hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847\n|  hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|\n| Freed by task 322:\n|  hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]\n|  hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736\n|  hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405\n|  hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]\n|  hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679\n|  vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690\n|  __fput+0x369/0x890 fs/file_table.c:510\n|  task_work_run+0x160/0x1d0 kernel/task_work.c:233\n|  get_signal+0xf5b/0x1120 kernel/signal.c:2810\n|  arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337\n|  __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]\n|  exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98\n|  do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100\n|  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n|\n| The buggy address belongs to the object at ffff8881298d9400\n|  which belongs to the cache kmalloc-512 of size 512\n| The buggy address is located 336 bytes inside of\n|  freed 512-byte region [ffff8881298d9400, ffff8881298d9600)\n\nFix it by having chan->conn hold a reference to l2cap_conn (via\nl2cap_conn_get) when the channel is added to the connection, and\nreleasing it in the channel destructor. This ensures the l2cap_conn\nremains alive as long as the channel exists.\n\nA new FLAG_DEL channel flag is introduced to indicate that the ch\n---truncated---"}],"providerMetadata":{"dateUpdated":"2026-07-25T08:51:09.066Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189"},{"url":"https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d"},{"url":"https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032"},{"url":"https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277"},{"url":"https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b"}],"title":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64434","datePublished":"2026-07-25T08:51:09.066Z","dateReserved":"2026-07-19T15:36:31.787Z","dateUpdated":"2026-07-25T08:51:09.066Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:27","lastModifiedDate":"2026-07-25 10:17:27","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64434","Ordinal":"1","Title":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref","CVE":"CVE-2026-64434","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64434","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\n\nl2cap_chan_timeout() runs asynchronously and accesses chan->conn. If\nthe connection is torn down while the timer is running or pending,\nchan->conn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn->lock:\n\n| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83\n|\n| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)\n| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\n| Workqueue: events l2cap_chan_timeout\n| Call Trace:\n|  <TASK>\n|  instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n|  atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n|  __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n|  mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n|  l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|  </TASK>\n|\n| Allocated by task 320:\n|  l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075\n|  l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452\n|  hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]\n|  hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760\n|  hci_event_func net/bluetooth/hci_event.c:7796 [inline]\n|  hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847\n|  hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040\n|  process_one_work kernel/workqueue.c:3326 [inline]\n|  process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n|  worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n|  kthread+0x346/0x430 kernel/kthread.c:436\n|  ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n|  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|\n| Freed by task 322:\n|  hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]\n|  hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736\n|  hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405\n|  hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]\n|  hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679\n|  vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690\n|  __fput+0x369/0x890 fs/file_table.c:510\n|  task_work_run+0x160/0x1d0 kernel/task_work.c:233\n|  get_signal+0xf5b/0x1120 kernel/signal.c:2810\n|  arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337\n|  __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]\n|  exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98\n|  do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100\n|  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n|\n| The buggy address belongs to the object at ffff8881298d9400\n|  which belongs to the cache kmalloc-512 of size 512\n| The buggy address is located 336 bytes inside of\n|  freed 512-byte region [ffff8881298d9400, ffff8881298d9600)\n\nFix it by having chan->conn hold a reference to l2cap_conn (via\nl2cap_conn_get) when the channel is added to the connection, and\nreleasing it in the channel destructor. This ensures the l2cap_conn\nremains alive as long as the channel exists.\n\nA new FLAG_DEL channel flag is introduced to indicate that the ch\n---truncated---","Type":"Description","Title":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref"}]}}}