linux-kernel - [PATCH] net/bluetooth: Fix bound check in event handling

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Message-Id: <20190304202043.3691-1-tomasbortoli@gmail.com>
Date:   Mon,  4 Mar 2019 21:20:43 +0100
From:   Tomas Bortoli <tomasbortoli@...il.com>
To:     marcel@...tmann.org, johan.hedberg@...il.com
Cc:     davem@...emloft.net, linux-bluetooth@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller@...glegroups.com, Tomas Bortoli <tomasbortoli@...il.com>
Subject: [PATCH] net/bluetooth: Fix bound check in event handling

hci_inquiry_result_with_rssi_evt() can perform out of bound reads
on skb->data as a bound check is missing.

Signed-off-by: Tomas Bortoli <tomasbortoli@...il.com>
Reported-by: syzbot+cec7a50c412a2c03f8f5@...kaller.appspotmail.com
Reported-by: syzbot+660883c56e2fa65d4497@...kaller.appspotmail.com
---
v2: 
 - changed sizeof(info) into sizeof(*info), as it should be. 
 - simplified expression in if

 net/bluetooth/hci_event.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac2826ce162b..4cbad1e1a322 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3978,11 +3978,15 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
 
 	if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
 		struct inquiry_info_with_rssi_and_pscan_mode *info;
+		void *data_end = (void *)skb->data + skb->len;
 		info = (void *) (skb->data + 1);
 
 		for (; num_rsp; num_rsp--, info++) {
 			u32 flags;
 
+			if ((void *)info + sizeof(*info) > data_end)
+				break;
+
 			bacpy(&data.bdaddr, &info->bdaddr);
 			data.pscan_rep_mode	= info->pscan_rep_mode;
 			data.pscan_period_mode	= info->pscan_period_mode;
-- 
2.11.0