Description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: Fix initial port reference race
For RFCOMM_RELEASE_ONHUP devices, rfcomm_tty_install() and
__rfcomm_release_dev() both use RFCOMM_TTY_OWNED to decide who drops the
initial tty_port reference. The release path tests the bit separately
from the install path setting it, so both can drop that reference.
The synchronous hangup does not prevent this race: port->tty is not
assigned until tty_port_open(), after installation. The following
interleaving is possible:
1. Install and release each obtain a reference with rfcomm_dev_get().
2. Release observes RFCOMM_TTY_OWNED clear.
3. Install sets RFCOMM_TTY_OWNED and drops the initial reference.
4. Release drops the same initial reference again.
5. TTY cleanup drops its reference and frees the device.
6. Release performs its final tty_port_put() on the freed port.
KASAN reported:
BUG: KASAN: slab-use-after-free in tty_port_put+0x22/0x190
Write of size 4 at addr ffff8881001d3d5c by task poc/92
Call Trace:
tty_port_put+0x22/0x190
rfcomm_dev_ioctl+0x1d4/0x1930
sock_do_ioctl+0x110/0x260
sock_ioctl+0x380/0x590
__x64_sys_ioctl+0x134/0x1c0
Allocated by task 88:
rfcomm_dev_ioctl+0x8f6/0x1930
sock_do_ioctl+0x110/0x260
sock_ioctl+0x380/0x590
__x64_sys_ioctl+0x134/0x1c0
Freed by task 65:
kfree+0x131/0x3c0
rfcomm_dev_destruct+0x23b/0x2f0
release_one_tty+0xc1/0x370
process_one_work+0x661/0x1090
Use test_and_set_bit() in both paths so that only the caller that changes
RFCOMM_TTY_OWNED from clear to set drops the initial reference. Each path
keeps its own lookup reference until release or TTY cleanup, preserving
the existing callback ordering and error handling.
Bluetooth: RFCOMM: Fix initial port reference race
For RFCOMM_RELEASE_ONHUP devices, rfcomm_tty_install() and
__rfcomm_release_dev() both use RFCOMM_TTY_OWNED to decide who drops the
initial tty_port reference. The release path tests the bit separately
from the install path setting it, so both can drop that reference.
The synchronous hangup does not prevent this race: port->tty is not
assigned until tty_port_open(), after installation. The following
interleaving is possible:
1. Install and release each obtain a reference with rfcomm_dev_get().
2. Release observes RFCOMM_TTY_OWNED clear.
3. Install sets RFCOMM_TTY_OWNED and drops the initial reference.
4. Release drops the same initial reference again.
5. TTY cleanup drops its reference and frees the device.
6. Release performs its final tty_port_put() on the freed port.
KASAN reported:
BUG: KASAN: slab-use-after-free in tty_port_put+0x22/0x190
Write of size 4 at addr ffff8881001d3d5c by task poc/92
Call Trace:
tty_port_put+0x22/0x190
rfcomm_dev_ioctl+0x1d4/0x1930
sock_do_ioctl+0x110/0x260
sock_ioctl+0x380/0x590
__x64_sys_ioctl+0x134/0x1c0
Allocated by task 88:
rfcomm_dev_ioctl+0x8f6/0x1930
sock_do_ioctl+0x110/0x260
sock_ioctl+0x380/0x590
__x64_sys_ioctl+0x134/0x1c0
Freed by task 65:
kfree+0x131/0x3c0
rfcomm_dev_destruct+0x23b/0x2f0
release_one_tty+0xc1/0x370
process_one_work+0x661/0x1090
Use test_and_set_bit() in both paths so that only the caller that changes
RFCOMM_TTY_OWNED from clear to set drops the initial reference. Each path
keeps its own lookup reference until release or TTY cleanup, preserving
the existing callback ordering and error handling.
Published:
2026-10-18
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
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References
History
Sun, 18 Oct 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: Fix initial port reference race For RFCOMM_RELEASE_ONHUP devices, rfcomm_tty_install() and __rfcomm_release_dev() both use RFCOMM_TTY_OWNED to decide who drops the initial tty_port reference. The release path tests the bit separately from the install path setting it, so both can drop that reference. The synchronous hangup does not prevent this race: port->tty is not assigned until tty_port_open(), after installation. The following interleaving is possible: 1. Install and release each obtain a reference with rfcomm_dev_get(). 2. Release observes RFCOMM_TTY_OWNED clear. 3. Install sets RFCOMM_TTY_OWNED and drops the initial reference. 4. Release drops the same initial reference again. 5. TTY cleanup drops its reference and frees the device. 6. Release performs its final tty_port_put() on the freed port. KASAN reported: BUG: KASAN: slab-use-after-free in tty_port_put+0x22/0x190 Write of size 4 at addr ffff8881001d3d5c by task poc/92 Call Trace: tty_port_put+0x22/0x190 rfcomm_dev_ioctl+0x1d4/0x1930 sock_do_ioctl+0x110/0x260 sock_ioctl+0x380/0x590 __x64_sys_ioctl+0x134/0x1c0 Allocated by task 88: rfcomm_dev_ioctl+0x8f6/0x1930 sock_do_ioctl+0x110/0x260 sock_ioctl+0x380/0x590 __x64_sys_ioctl+0x134/0x1c0 Freed by task 65: kfree+0x131/0x3c0 rfcomm_dev_destruct+0x23b/0x2f0 release_one_tty+0xc1/0x370 process_one_work+0x661/0x1090 Use test_and_set_bit() in both paths so that only the caller that changes RFCOMM_TTY_OWNED from clear to set drops the initial reference. Each path keeps its own lookup reference until release or TTY cleanup, preserving the existing callback ordering and error handling. | |
| Title | Bluetooth: RFCOMM: Fix initial port reference race | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-18T15:47:23.653Z
Reserved: 2026-09-25T10:25:14.367Z
Link: CVE-2026-98739
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-18T16:17:27.590
Modified: 2026-10-18T16:17:27.590
Link: CVE-2026-98739
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.