Riskcovery

CVE-2026-98739

Bluetooth: RFCOMM: Fix initial port reference race

State
Published
Severity
Not scored
Published
Oct 18, 2026
Updated
Oct 30, 2026
Reserved
Sep 25, 2026

Read the record on cve.org

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before cd247e38b14df48d6b3940c4573a9f7acb10c363Affected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before d3dd18e85c140df72e0f2b5ee156ebfba04c06cbAffected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before c50360a019766fafa27318928bfea96dcce8a37dAffected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before 55d162aa00d1ee33c3e6fa88b71f1e2d6e1441e9Affected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before a03ccf1ab77380d4c4a3c56552e12de4a83efa21Affected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before 0a554901bd227537f79220443b2b36d585d62893Affected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before e5aa7fbf7a4446bb89f0b8394b2dfc1a6b6aba5bAffected
  • 80ea73378af46b0023eb2f400d26c2a60248ffaa to before 2d696c1ed3468dcb62578a3911e687110d463520Affected
LinuxLinux
  • 3.15Affected
  • before 3.15Not affected
  • 5.10.273 through 5.10.*Not affected
  • 5.15.224 through 5.15.*Not affected
  • 6.1.191 through 6.1.*Not affected
  • 6.6.160 through 6.6.*Not affected
  • 6.12.113 through 6.12.*Not affected
  • 6.18.56 through 6.18.*Not affected
  • 7.2.10 through 7.2.*Not affected
  • 7.3 and laterNot affected

References

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