From 711f8c3fb3db61897080468586b970c87c61d9e4 Mon Sep 17 00:00:00 2001
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date: Mon, 31 Oct 2022 16:10:32 -0700
Subject: [PATCH] Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM
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Git-commit: 711f8c3fb3db61897080468586b970c87c61d9e4
Patch-mainline: v6.1-rc4
References: CVE-2022-42896 bsc#1205709

[ backport note: dropped the change for l2cap_ecred_conn_req() as this
  kernel branch has no corresponding code yet. Also replaced
  L2CAP_CR_LE_BAD_PSM with L2CAP_CR_BAD_PSM -- tiwai ]

The Bluetooth spec states that the valid range for SPSM is from
0x0001-0x00ff so it is invalid to accept values outside of this range:

  BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
  page 1059:
  Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges

Cve: CVE-2022-42896
Cc: stable@vger.kernel.org
Reported-by: Tamás Koczka <poprdi@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Reviewed-by: Tedd Ho-Jeong An <tedd.an@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/bluetooth/l2cap_core.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -5502,6 +5502,19 @@ static int l2cap_le_connect_req(struct l
 	BT_DBG("psm 0x%2.2x scid 0x%4.4x mtu %u mps %u", __le16_to_cpu(psm),
 	       scid, mtu, mps);
 
+	/* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
+	 * page 1059:
+	 *
+	 * Valid range: 0x0001-0x00ff
+	 *
+	 * Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges
+	 */
+	if (!psm || __le16_to_cpu(psm) > L2CAP_PSM_LE_DYN_END) {
+		result = L2CAP_CR_BAD_PSM;
+		chan = NULL;
+		goto response;
+	}
+
 	/* Check if we have socket listening on psm */
 	pchan = l2cap_global_chan_by_psm(BT_LISTEN, psm, &conn->hcon->src,
 					 &conn->hcon->dst, LE_LINK);