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[45.78.65.84]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-327f90c0dd3sm8622622eec.7.2026.08.22.09.43.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 22 Aug 2026 09:43:53 -0700 (PDT) From: Chengfeng Ye To: Marcel Holtmann , Luiz Augusto von Dentz , Kees Cook , Jakub Kicinski , Chengfeng Ye , Ali Ahmet Memis , Tim Bird , SeungJu Cheon , Gustavo Padovan , Dean Jenkins Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] Bluetooth: RFCOMM: serialize security confirmation handling Date: Sun, 23 Aug 2026 00:43:41 +0800 Message-ID: <20260822164341.3750491-1-nicoyip.dev@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rfcomm_security_cfm() looks up a session on session_list and then walks its DLC list without holding rfcomm_mutex. Since RFCOMM session teardown uses rfcomm_mutex, krfcommd can close and free the same session and DLCs concurrently: hci_rx_work krfcommd ----------- --------- rfcomm_session_get() rfcomm_lock() rfcomm_session_close() rfcomm_dlc_unlink() rfcomm_session_del() kfree(s) rfcomm_unlock() walk s->dlcs The callback can then read a freed session list head and touch freed DLCs while updating their flags or timers. Serialize the session lookup and DLC traversal in rfcomm_security_cfm() with rfcomm_mutex. This matches the existing RFCOMM session lifetime rules and prevents concurrent rfcomm_session_del() / rfcomm_dlc_unlink() from tearing the objects down while the callback is using them. KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_security_cfm+0x41c/0x440 Read of size 8 at addr ffff888111fb3960 by task kworker/u17:1/89 Workqueue: hci0 hci_rx_work Call Trace: rfcomm_security_cfm+0x41c/0x440 hci_encrypt_cfm+0x139/0x590 hci_encrypt_change_evt+0x37b/0xc40 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 Allocated by task 69: rfcomm_session_add+0x9e/0x2f0 rfcomm_run+0x44b/0x41e0 Freed by task 69: kfree+0x131/0x3c0 rfcomm_session_del+0x188/0x220 rfcomm_run+0x1985/0x41e0 Fixes: 08c30aca9e698faddebd34f81e1196295f9dc063 ("Bluetooth: Remove RFCOMM session refcnt") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye --- net/bluetooth/rfcomm/core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c index 9cdfea666a2c..5d150e8623d5 100644 --- a/net/bluetooth/rfcomm/core.c +++ b/net/bluetooth/rfcomm/core.c @@ -2213,9 +2213,13 @@ static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt) BT_DBG("conn %p status 0x%02x encrypt 0x%02x", conn, status, encrypt); + rfcomm_lock(); + s = rfcomm_session_get(&conn->hdev->bdaddr, &conn->dst); - if (!s) + if (!s) { + rfcomm_unlock(); return; + } list_for_each_entry_safe(d, n, &s->dlcs, list) { if (test_and_clear_bit(RFCOMM_SEC_PENDING, &d->flags)) { @@ -2247,6 +2251,8 @@ static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt) set_bit(RFCOMM_AUTH_REJECT, &d->flags); } + rfcomm_unlock(); + rfcomm_schedule(); } -- 2.43.0