[PATCH v2] Bluetooth: iso: Fix UAF on iso_sock_disconn

[Yang Li via B4 Relay <devnull+yang.li.amlogic.com@kernel.org>]

From: Yang Li <yang.li@amlogic.com>

When the phone stops audio sharing, it terminates the BIG first
and then sends BASS modify and remove operation codes to clear
the shared BIG. If a BIG sync lost event occurs at the same time,
the BIG connection may already be deleted. Releasing the socket
in this case can lead to a NULL connection pointer.

kernel panic: Unable to handle kernel read from unreadable
memory at virtual address 00000000000003d8
Call trace:
 iso_sock_disconn+0x110/0x1c8
 __iso_sock_close+0x50/0x164
 iso_sock_release+0x48/0xf0
 __sock_release+0x40/0xb4
 sock_close+0x18/0x28
 __fput+0xd8/0x28c
 __fput_sync+0x50/0x5c
 __arm64_sys_close+0x38/0x7c
 invoke_syscall+0x48/0x118
 el0_svc_common.constprop.0+0x40/0xe0
 do_el0_svc_compat+0x1c/0x34
 el0_svc_compat+0x30/0x88
 el0t_32_sync_handler+0x90/0x140
 el0t_32_sync+0x198/0x19c

Signed-off-by: Yang Li <yang.li@amlogic.com>
---
Changes in v2:
- Add description about this problem
- Link to v1: https://lore.kernel.org/r/20251105-kernel_panic-v1-1-88637054c6b9@amlogic.com
---
 net/bluetooth/iso.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 74ec7d125c88..89c7700ceb81 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -838,14 +838,14 @@ static void __iso_sock_close(struct sock *sk)
 	case BT_CONNECT:
 	case BT_CONNECTED:
 	case BT_CONFIG:
-		if (iso_pi(sk)->conn->hcon)
+		if (iso_pi(sk)->conn && iso_pi(sk)->conn->hcon)
 			iso_sock_disconn(sk);
 		else
 			iso_chan_del(sk, ECONNRESET);
 		break;
 
 	case BT_CONNECT2:
-		if (iso_pi(sk)->conn->hcon &&
+		if (iso_pi(sk)->conn && iso_pi(sk)->conn->hcon &&
 		    (test_bit(HCI_CONN_PA_SYNC, &iso_pi(sk)->conn->hcon->flags) ||
 		    test_bit(HCI_CONN_PA_SYNC_FAILED, &iso_pi(sk)->conn->hcon->flags)))
 			iso_sock_disconn(sk);

---
base-commit: 2747d929617743ecba08eeeb310283b4be681383
change-id: 20251105-kernel_panic-73adc703480d

Best regards,
-- 
Yang Li <yang.li@amlogic.com>