linux-kernel - [PATCH AUTOSEL 6.11 79/87] Bluetooth: hci_core: Fix not checking skb length on hci_acldata

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Message-ID: <20241124134102.3344326-79-sashal@kernel.org>
Date: Sun, 24 Nov 2024 08:38:57 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
	syzbot+6ea290ba76d8c1eb1ac2@...kaller.appspotmail.com,
	Sasha Levin <sashal@...nel.org>,
	marcel@...tmann.org,
	johan.hedberg@...il.com,
	luiz.dentz@...il.com,
	linux-bluetooth@...r.kernel.org
Subject: [PATCH AUTOSEL 6.11 79/87] Bluetooth: hci_core: Fix not checking skb length on hci_acldata_packet

From: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>

[ Upstream commit 3fe288a8214e7dd784d1f9b7c9e448244d316b47 ]

This fixes not checking if skb really contains an ACL header otherwise
the code may attempt to access some uninitilized/invalid memory past the
valid skb->data.

Reported-by: syzbot+6ea290ba76d8c1eb1ac2@...kaller.appspotmail.com
Tested-by: syzbot+6ea290ba76d8c1eb1ac2@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/bluetooth/hci_core.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index eeb4f025ca3bf..bda70d0268e09 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3771,18 +3771,22 @@ static void hci_tx_work(struct work_struct *work)
 /* ACL data packet */
 static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 {
-	struct hci_acl_hdr *hdr = (void *) skb->data;
+	struct hci_acl_hdr *hdr;
 	struct hci_conn *conn;
 	__u16 handle, flags;
 
-	skb_pull(skb, HCI_ACL_HDR_SIZE);
+	hdr = skb_pull_data(skb, sizeof(*hdr));
+	if (!hdr) {
+		bt_dev_err(hdev, "ACL packet too small");
+		goto drop;
+	}
 
 	handle = __le16_to_cpu(hdr->handle);
 	flags  = hci_flags(handle);
 	handle = hci_handle(handle);
 
-	BT_DBG("%s len %d handle 0x%4.4x flags 0x%4.4x", hdev->name, skb->len,
-	       handle, flags);
+	bt_dev_dbg(hdev, "len %d handle 0x%4.4x flags 0x%4.4x", skb->len,
+		   handle, flags);
 
 	hdev->stat.acl_rx++;
 
@@ -3801,6 +3805,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 			   handle);
 	}
 
+drop:
 	kfree_skb(skb);
 }
 
-- 
2.43.0