[PATCH 1/2 6.6.y] Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID

[Jeremy Erazo]

commit f4da3ee15de99efa0a68eae1c4d09b4bcc6d9dcd upstream.

Copy the content of a Periodic Advertisement Report to BASE only if
the service UUID is Basic Audio Announcement Service UUID.

[Stable backport rationale]

This fix landed in mainline v6.7 without a Fixes: tag, so the stable
autoselect bot never picked it up.  linux-6.6.y HEAD (v6.6.143) still
carries the pre-fix code at net/bluetooth/iso.c:1935:

	if (sk) {
		memcpy(iso_pi(sk)->base, ev3->data, ev3->length);
		iso_pi(sk)->base_len = ev3->length;
	}

ev3->length is __u8 and iso_pi(sk)->base is __u8[BASE_MAX_LENGTH] where
BASE_MAX_LENGTH is HCI_MAX_PER_AD_LENGTH(252) - EIR_SERVICE_DATA_LENGTH(4)
= 248.  When an attacker within BLE radio range sends an HCI_EV_LE_PER_ADV_REPORT
with ev3->length in [249, 255], the memcpy writes 1 to 7 bytes past the
buffer into the trailing fields of struct iso_pinfo, including the low
bytes of the iso_pi(sk)->conn pointer.  FORTIFY_SOURCE flags the write
with "memcpy: detected field-spanning write" but does not block it.

The upstream refactor addresses this by:
  1. Filtering via eir_get_service_data() so only the BASE portion of
     the PA payload is copied.
  2. Bounding the copy with base_len <= sizeof(iso_pi(sk)->base).

The refactor applies cleanly against v6.6.143 - eir_get_service_data(),
EIR_BAA_SERVICE_UUID, and BASE_MAX_LENGTH already exist in the 6.6.y
tree.

Reachability: any host with an ISO listening socket bound as a
broadcast sink (LE Audio / Auracast).  No pairing required.

Fixes: 9c0826310bfb ("Bluetooth: ISO: Add support for periodic adv reports processing")
Cc: stable@xxxxxxxxxxxxxxx # 6.6.y
Signed-off-by: Claudia Draghicescu <claudia.rosu@xxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
[jerazo: backport to 6.6.y, no context conflicts]
Signed-off-by: Jeremy Erazo <mendozayt13@xxxxxxxxx>
---
 net/bluetooth/iso.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 011b2187b..8843bd5c5 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -14,6 +14,7 @@
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
 #include <net/bluetooth/iso.h>
+#include "eir.h"
 
 static const struct proto_ops iso_sock_ops;
 
@@ -47,6 +48,7 @@ static void iso_sock_kill(struct sock *sk);
 
 #define EIR_SERVICE_DATA_LENGTH 4
 #define BASE_MAX_LENGTH (HCI_MAX_PER_AD_LENGTH - EIR_SERVICE_DATA_LENGTH)
+#define EIR_BAA_SERVICE_UUID	0x1851
 
 /* iso_pinfo flags values */
 enum {
@@ -1587,6 +1589,8 @@ static int iso_sock_getsockopt(struct socket *sock, int level, int optname,
 		len = min_t(unsigned int, len, base_len);
 		if (copy_to_user(optval, base, len))
 			err = -EFAULT;
+		if (put_user(len, optlen))
+			err = -EFAULT;
 
 		break;
 
@@ -1928,12 +1932,16 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 
 	ev3 = hci_recv_event_data(hdev, HCI_EV_LE_PER_ADV_REPORT);
 	if (ev3) {
+		size_t base_len = ev3->length;
+		u8 *base;
+
 		sk = iso_get_sock_listen(&hdev->bdaddr, bdaddr,
 					 iso_match_sync_handle_pa_report, ev3);
-
-		if (sk) {
-			memcpy(iso_pi(sk)->base, ev3->data, ev3->length);
-			iso_pi(sk)->base_len = ev3->length;
+		base = eir_get_service_data(ev3->data, ev3->length,
+					    EIR_BAA_SERVICE_UUID, &base_len);
+		if (base && sk && base_len <= sizeof(iso_pi(sk)->base)) {
+			memcpy(iso_pi(sk)->base, base, base_len);
+			iso_pi(sk)->base_len = base_len;
 		}
 	} else {
 		sk = iso_get_sock_listen(&hdev->bdaddr, BDADDR_ANY, NULL, NULL);
-- 
2.53.0