linux-kernel - [PATCH AUTOSEL 4.9 08/12] Bluetooth: Fix null pointer dereference in amp_read_loc_assoc_final

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Message-Id: <20210224125540.484221-8-sashal@kernel.org>
Date:   Wed, 24 Feb 2021 07:55:36 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Gopal Tiwari <gtiwari@...hat.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Sasha Levin <sashal@...nel.org>,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 08/12] Bluetooth: Fix null pointer dereference in amp_read_loc_assoc_final_data

From: Gopal Tiwari <gtiwari@...hat.com>

[ Upstream commit e8bd76ede155fd54d8c41d045dda43cd3174d506 ]

kernel panic trace looks like:

 #5 [ffffb9e08698fc80] do_page_fault at ffffffffb666e0d7
 #6 [ffffb9e08698fcb0] page_fault at ffffffffb70010fe
    [exception RIP: amp_read_loc_assoc_final_data+63]
    RIP: ffffffffc06ab54f  RSP: ffffb9e08698fd68  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: ffff8c8845a5a000  RCX: 0000000000000004
    RDX: 0000000000000000  RSI: ffff8c8b9153d000  RDI: ffff8c8845a5a000
    RBP: ffffb9e08698fe40   R8: 00000000000330e0   R9: ffffffffc0675c94
    R10: ffffb9e08698fe58  R11: 0000000000000001  R12: ffff8c8b9cbf6200
    R13: 0000000000000000  R14: 0000000000000000  R15: ffff8c8b2026da0b
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffffb9e08698fda8] hci_event_packet at ffffffffc0676904 [bluetooth]
 #8 [ffffb9e08698fe50] hci_rx_work at ffffffffc06629ac [bluetooth]
 #9 [ffffb9e08698fe98] process_one_work at ffffffffb66f95e7

hcon->amp_mgr seems NULL triggered kernel panic in following line inside
function amp_read_loc_assoc_final_data

        set_bit(READ_LOC_AMP_ASSOC_FINAL, &mgr->state);

Fixed by checking NULL for mgr.

Signed-off-by: Gopal Tiwari <gtiwari@...hat.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/bluetooth/amp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/bluetooth/amp.c b/net/bluetooth/amp.c
index e32f341890079..b01b43ab6f834 100644
--- a/net/bluetooth/amp.c
+++ b/net/bluetooth/amp.c
@@ -305,6 +305,9 @@ void amp_read_loc_assoc_final_data(struct hci_dev *hdev,
 	struct hci_request req;
 	int err = 0;
 
+	if (!mgr)
+		return;
+
 	cp.phy_handle = hcon->handle;
 	cp.len_so_far = cpu_to_le16(0);
 	cp.max_len = cpu_to_le16(hdev->amp_assoc_size);
-- 
2.27.0