Patch "Bluetooth: hci_core: Fix not checking skb length on hci_acldata_packet" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: hci_core: Fix not checking skb length on hci_acldata_packet

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-hci_core-fix-not-checking-skb-length-on-hc.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ad3aef8c82e3296343857c8f081fb4ddf107bd03
Author: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Date:   Tue Oct 8 10:16:48 2024 -0400

    Bluetooth: hci_core: Fix not checking skb length on hci_acldata_packet
    
    [ 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@xxxxxxxxxxxxxxxxxxxxxxxxx
    Tested-by: syzbot+6ea290ba76d8c1eb1ac2@xxxxxxxxxxxxxxxxxxxxxxxxx
    Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 7dff3f1a2a9eb..7ed5d6e47e4f3 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4943,18 +4943,22 @@ 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++;
 
@@ -4973,6 +4977,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 			   handle);
 	}
 
+drop:
 	kfree_skb(skb);
 }