---
id: CVE-2026-98455
title: 'Bluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO

  The RFCOMM_CONNINFO getsockopt handler accepts a socket that is not
  connected as long as def…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    c3aee3fc1287c8a555baf3895959087cb0c33fe8
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    4bf5ca47203049ce3648f750a53dcdc98bcc9e3e
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    1c4f7e1177da2f229be04139c27e5370a1cfba52
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    84ae3cfd7d3a63591a2eb4faa24faf678c6708aa
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    c7362f6a18ed167f52f08ce25eeec8a7818c5004
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    8f5b30cc12c409ff62891e47ed51e6bf0945a3ea
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    005b23d9e324fe5d0acbcfa70c625f2e81189046
  - >-
    Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 <
    46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1
  - Linux 2.6.30
published: '2026-10-18'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T09:19:50.740Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98455'
references:
  - url: 'https://git.kernel.org/stable/c/c3aee3fc1287c8a555baf3895959087cb0c33fe8'
  - url: 'https://git.kernel.org/stable/c/4bf5ca47203049ce3648f750a53dcdc98bcc9e3e'
  - url: 'https://git.kernel.org/stable/c/1c4f7e1177da2f229be04139c27e5370a1cfba52'
  - url: 'https://git.kernel.org/stable/c/84ae3cfd7d3a63591a2eb4faa24faf678c6708aa'
  - url: 'https://git.kernel.org/stable/c/c7362f6a18ed167f52f08ce25eeec8a7818c5004'
  - url: 'https://git.kernel.org/stable/c/8f5b30cc12c409ff62891e47ed51e6bf0945a3ea'
  - url: 'https://git.kernel.org/stable/c/005b23d9e324fe5d0acbcfa70c625f2e81189046'
  - url: 'https://git.kernel.org/stable/c/46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.304Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO

The RFCOMM_CONNINFO getsockopt handler accepts a socket that is not
connected as long as deferred setup is enabled:

	if (sk->sk_state != BT_CONNECTED &&
				!rfcomm_pi(sk)->dlc->defer_setup) {
		err = -ENOTCONN;
		break;
	}
	l2cap_sk = rfcomm_pi(sk)->dlc->session->sock->sk;

dlc->defer_setup is set in rfcomm_sock_init() when rfcomm_connect_ind()
creates a child socket for an incoming connection on a listening socket
that has BT_DEFER_SETUP enabled. It is never cleared afterwards. The
session, however, can go away underneath it.

rfcomm_recv_disc() forces the dlc state before tearing it down:

	d->state = BT_CLOSED;
	__rfcomm_dlc_close(d, err);

The RFCOMM_DEFER_SETUP early return in __rfcomm_dlc_close() only covers
BT_CONNECT, BT_CONFIG, BT_OPEN and BT_CONNECT2, so with the state
already BT_CLOSED that switch does not match and the function falls
through to rfcomm_dlc_unlink(), which sets d->session = NULL, while
d->defer_setup stays 1.

A getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted socket after
that point therefore skips the -ENOTCONN path -- sk->sk_state is
BT_CLOSED, but dlc->defer_setup is still set -- and dereferences the
NULL session. No race is needed: once the DISC has been processed, the
dereference is unconditional.

Reproduced on a KASAN kernel under QEMU with a BR/EDR peer emulated over
/dev/vhci: the peer brings up an ACL link, opens L2CAP on the RFCOMM
PSM, starts a session and sends SABM for a channel bound with
BT_DEFER_SETUP, and sends DISC for that dlci after the socket has been
accepted. getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted
socket then hits:

 Oops: general protection fault, probably for non-canonical address
 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI
 KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
 CPU: 1 UID: 0 PID: 150 Comm: init Tainted: G B 7.3.0-rc3-g5dd1818b15d9
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
 RIP: 0010:rfcomm_sock_getsockopt+0x529/0x780
 Call Trace:
  <TASK>
  do_sock_getsockopt+0x3ad/0x7d0
  __sys_getsockopt+0x10e/0x1b0
  __x64_sys_getsockopt+0xc2/0x160
  do_syscall_64+0xda/0x4b0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
  </TASK>

0x10 is the offset of sock in struct rfcomm_session;
rfcomm_sock_getsockopt_old() is inlined into rfcomm_sock_getsockopt().

Commit 43a556b2fd43 ("Bluetooth: RFCOMM: take rfcomm_mutex for the
deferred setup accept") fixed the same "a remote DISC clears the session
while deferred setup is still flagged" problem in rfcomm_dlc_accept();
this is the remaining instance of it, in the getsockopt path.

Deferred setup only leaves a socket usable here once it has reached
BT_CONNECT2, so restrict the exception to that state and check that a
session is actually present before following it.

## Affected

- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c3aee3fc1287c8a555baf3895959087cb0c33fe8`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 4bf5ca47203049ce3648f750a53dcdc98bcc9e3e`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 1c4f7e1177da2f229be04139c27e5370a1cfba52`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 84ae3cfd7d3a63591a2eb4faa24faf678c6708aa`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c7362f6a18ed167f52f08ce25eeec8a7818c5004`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 8f5b30cc12c409ff62891e47ed51e6bf0945a3ea`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 005b23d9e324fe5d0acbcfa70c625f2e81189046`
- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1`
- `Linux 2.6.30`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.