Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths

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Summary

CVECVE-2026-46275
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-08 16:16:40 UTC
Updated2026-06-08 16:16:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths Vulnerabilities leading to Use-After-Free (UAF) and Null Pointer Dereference (NPD) conditions were observed in the lifecycle management of hci_uart. The primary issue arises because the workqueues (init_ready and write_work) are only flushed/cancelled if the HCI_UART_PROTO_READY flag is set during TTY close. If a hangup occurs before setup completes, hci_uart_tty_close() skips the teardown of these workqueues and proceeds to free the `hu` struct. When the scheduled work executes later, it blindly dereferences the freed `hu` struct. Furthermore, several data races and UAFs were identified in the teardown sequence: 1. Calling hci_uart_flush() from hci_uart_close() without effectively disabling write_work causes a race condition where both can concurrently double-free hu->tx_skb. This happens because protocol timers can concurrently invoke hci_uart_tx_wakeup() and requeue write_work. 2. Calling hci_free_dev(hdev) before hu->proto->close(hu) causes a UAF when vendor specific protocol close callbacks dereference hu->hdev. 3. In the initialization error paths, failing to take the proto_lock write lock before clearing PROTO_READY leads to races with active readers. Additionally, hci_uart_tty_receive() accesses hu->hdev outside the read lock, leading to UAFs if the initialization error path frees hdev concurrently. Fix these synchronization and lifecycle issues by: 1. Re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first, followed immediately by a cancel_work_sync(&hu->write_work). Clearing the flag locks out concurrent protocol timers from successfully invoking hci_uart_tx_wakeup(), effectively rendering the cancellation permanent and preventing the tx_skb double-free. 2. Note: Clearing PROTO_READY early causes hci_uart_close() to skip hu->proto->flush(). This is perfectly safe in the tty_close path because hu->proto->close() executes shortly after, which intrinsically purges all protocol SKB queues and tears down the state. 3. Relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev) across all close and error paths to prevent vendor-level UAFs. 4. Moving the hdev->stat.byte_rx increment in hci_uart_tty_receive() inside the proto_lock read-side critical section to safely synchronize with device unregistration. 5. Adding cancel_work_sync(&hu->write_work) to hci_uart_close() to safely flush the workqueue before hci_uart_flush() is invoked via the HCI core. 6. Utilizing cancel_work_sync() instead of disable_work_sync() across all paths to prevent permanently breaking user-space retry capabilities.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f 78aad93e938f013d9272fe0ee168f27883afa95c git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f e2d19969c8d9198ecc3090bcd5312ecd503a3339 git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f c85cff648a2bc92322912db5f1727ad05afae7b6 git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f 9d20d48be2c4a071fb015eb09bda2cecd25daf34 git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f 81c7a3c22a0f2808cf4ae0b4908f59763b23606d git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f 192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894 git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f 7338031946bd06f6dff149e67b60c4cd083bfea8 git Not specified
CNA Linux Linux affected 3b799254cf6f481460719023d7a18f46651e5e7f c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b git Not specified
CNA Linux Linux affected cd27019bc149f20f12ebec943c2b4c775745a5a0 git Not specified
CNA Linux Linux affected aea63181b6fcb6b9ccde1ada9ea51be19c4015af git Not specified
CNA Linux Linux affected 0d234d1135dcd8876de0576dac68efd0a87eef87 git Not specified
CNA Linux Linux affected 3fe978892ab46efc2f3830d9abc015eff72caaf9 git Not specified
CNA Linux Linux affected 0d987e14bebaf0f67ee7dbefaf6165c62cd1d27f git Not specified
CNA Linux Linux affected 4.14.203 4.15 semver Not specified
CNA Linux Linux affected 4.19.153 4.20 semver Not specified
CNA Linux Linux affected 5.4.73 5.5 semver Not specified
CNA Linux Linux affected 5.8.17 5.9 semver Not specified
CNA Linux Linux affected 5.9.2 5.10 semver Not specified
CNA Linux Linux affected 5.10 Not specified
CNA Linux Linux unaffected 5.10 semver Not specified
CNA Linux Linux unaffected 5.10.258 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.209 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.175 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.142 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.92 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.34 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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