Bluetooth: SCO: give the socket its own sco_conn reference

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80683
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 08:16:53 UTC
Updated2026-08-28 08:16:53 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: give the socket its own sco_conn reference sco_conn_del() drops a reference it does not own. It takes one transient reference via sco_conn_hold_unless_zero() and releases it with the sco_conn_put() that follows sco_sock_hold(); the additional put in the !sk branch releases a second one: conn = sco_conn_hold_unless_zero(conn); ... sk = sco_sock_hold(conn); sco_conn_unlock(conn); sco_conn_put(conn); if (!sk) { sco_conn_put(conn); return; } When close() races the controller's Disconnection Complete, sco_chan_del() clears conn->sk and drops the socket's reference while sco_conn_del() is running. sco_conn_del() then sees sk == NULL, its own put drops the count to zero and frees the conn, and the second put writes to the freed kref: BUG: KASAN: slab-use-after-free in sco_conn_put.part.0+0x1a/0x190 Write of size 4 at addr ffff8881099dec74 by task kworker/u17:3/413 Workqueue: hci1 hci_rx_work Call Trace: sco_conn_put.part.0+0x1a/0x190 hci_disconn_complete_evt+0x1ee/0x3e0 hci_event_packet+0x54a/0x650 hci_rx_work+0x321/0x3d0 Allocated by task 413: sco_conn_add+0x72/0x1a0 sco_connect_cfm+0x88/0x670 Freed by task 413: sco_conn_del.isra.0+0x3f/0xf0 hci_disconn_complete_evt+0x1ee/0x3e0 refcount_t: underflow; use-after-free. The root cause is that the socket stores the connection without holding a reference of its own. __sco_chan_add() does: sco_pi(sk)->conn = conn; so the socket borrows whatever reference its caller happened to hold, and the callers paper over that with ad-hoc holds and puts. Give the socket a counted reference instead: __sco_chan_add() takes one and it is released together with the channel (sco_chan_del()) and in sco_sock_destruct(). With the socket holding its own reference, sco_conn_del() no longer needs the extra put and the redundant hold in sco_conn_ready() goes away. Making the socket own its reference means the connection is now actually freed on the error paths of sco_connect() where it used to leak, which in turn runs sco_conn_free() and its hci_conn_drop(conn->hcon). To keep the hci_conn accounting balanced, make that ownership explicit as well: sco_conn_add() consumes one hci_conn reference and the sco_conn owns it for its lifetime. sco_connect() hands over the reference returned by hci_connect_sco() and no longer drops it on the error paths; sco_connect_cfm(), which is not given a reference, takes one with hci_conn_hold() before handing it to sco_conn_add() (and drops it again if the allocation fails); and the explicit hci_conn_hold() in sco_conn_ready() is removed. Every reference then has a single, clear owner.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected e6720779ae612a14ac4ba7fe4fd5b27d900d932c a33bc07b4730b6cd5681ac77d18ae0de3e739690 git Not specified
CNA Linux Linux affected e6720779ae612a14ac4ba7fe4fd5b27d900d932c 8fe627192fa5da7157f9a48608f13c04b6373e43 git Not specified
CNA Linux Linux affected e6720779ae612a14ac4ba7fe4fd5b27d900d932c abd93c85c8667add738ee82aeab95dd9fc8265a2 git Not specified
CNA Linux Linux affected 6.13 Not specified
CNA Linux Linux unaffected 6.13 semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a33bc07b4730b6cd5681ac77d18ae0de3e739690 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/abd93c85c8667add738ee82aeab95dd9fc8265a2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8fe627192fa5da7157f9a48608f13c04b6373e43 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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