Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98809
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:34 UTC
Updated2026-10-30 13:21:28 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister hci_unregister_dev() disables cmd_work and cmd_timer, then calls hci_cmd_sync_clear(), whose cancel_work_sync() waits for hci_cmd_sync_work() to return. That worker dequeues and runs every entry on cmd_sync_work_list. With cmd_work disabled nothing reaches the controller, so each queued HCI command waits the full HCI_CMD_TIMEOUT (2s). The backlog has no bound. Userspace can keep queuing MGMT commands such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't answer. Closing /dev/vhci then blocks in vhci_release() for backlog * 2s: INFO: task syz-executor:5749 blocked for more than 143 seconds. cancel_work_sync hci_cmd_sync_clear hci_unregister_dev vhci_release In a local reproduction the backlog held more than 5000 entries, which comes to hours of hang. Stop the worker from taking new entries once HCI_UNREGISTER is set, and wake any request still waiting with -ENODEV before cancelling the work. The entries left over are destroyed with -ECANCELED by the existing sweep in hci_cmd_sync_clear(). They stay on the list until the work has stopped, so hci_cmd_sync_dequeue() and friends still see them. A callback already running may still issue another command, which delays unregister by at most one timeout per remaining command, not by the whole backlog.

Risk And Classification

EPSS: 0.001720000 probability, percentile 0.066120000 (date 2026-11-01)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 b06d85b114cc5fa61809f9950bca66502e0e1173 git Not specified
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 b11acfcb5925ed27fae692b27931a1ac732677fb git Not specified
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 143bde97c4101ae68eb656c87e620c45b07a3090 git Not specified
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 7f16443a30f4e86d84ae4faf057d333b41ddb757 git Not specified
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c git Not specified
CNA Linux Linux affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 b1f24c1ab52345e810c42a1a81286cb5a7c92252 git Not specified
CNA Linux Linux affected 5.17 Not specified
CNA Linux Linux unaffected 5.17 semver Not specified
CNA Linux Linux unaffected 6.1.191 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.160 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.113 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.56 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.10 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b11acfcb5925ed27fae692b27931a1ac732677fb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b06d85b114cc5fa61809f9950bca66502e0e1173 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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