Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister
In 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.
CVE-2026-98809
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98809
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
"lessThan": "b11acfcb5925ed27fae692b27931a1ac732677fb",
"versionType": "git"
},
{
"status": "affected",
"version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
"lessThan": "143bde97c4101ae68eb656c87e620c45b07a3090",
"versionType": "git"
},
{
"status": "affected",
"version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
"lessThan": "7f16443a30f4e86d84ae4faf057d333b41ddb757",
"versionType": "git"
},
{
"status": "affected",
"version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
"lessThan": "e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c",
"versionType": "git"
},
{
"status": "affected",
"version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
"lessThan": "b1f24c1ab52345e810c42a1a81286cb5a7c92252",
"versionType": "git"
}
],
"programFiles": [
"net/bluetooth/hci_sync.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.17"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.17",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bluetooth/hci_sync.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98809
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48987 · Revision 1
- Added to Heist Feed
- Publisher date