[PATCH] Bluetooth: btnxpuart: Keep FW dump header in coredump chunks

[Ali Ahmet Memis <ali@iusegentoo.com>]

Commit 1fcf216462ec ("Bluetooth: btnxpuart: Validate the FW dump
header length") changed nxp_process_fw_dump() to use skb_pull_data()
when validating the FW dump header.

This also removes the header from skb->data. Since the skb is cloned
for hci_devcd_append() afterwards, the FW dump header is missing from
the coredump chunk.

The NXP FW dump analyzer expects nxp_fw_dump_hdr at the beginning of
each chunk, so this results in invalid coredumps.

Check the header length without pulling it from the skb instead. This
keeps skb->data pointing to the FW dump header when the skb is cloned.

Fixes: 1fcf216462ec ("Bluetooth: btnxpuart: Validate the FW dump header length")
Reported-by: Neeraj Kale <neeraj.sanjaykale@nxp.com>
Link: https://lore.kernel.org/linux-bluetooth/AS4PR04MB9692EC13E3176B6D7525D097E7A72@AS4PR04MB9692.eurprd04.prod.outlook.com/
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
---
Sorry for the late follow-up. I missed your reply on the v2 thread and
only noticed it after the change had landed. This patch restores the
approach from v2, as you suggested.

 drivers/bluetooth/btnxpuart.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index f2bbe6e462aa..16d0f709d4b7 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -1359,14 +1359,14 @@ static int nxp_process_fw_dump(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct hci_acl_hdr *acl_hdr = (struct hci_acl_hdr *)skb_pull_data(skb,
 									  sizeof(*acl_hdr));
-	struct nxp_fw_dump_hdr *fw_dump_hdr;
+	struct nxp_fw_dump_hdr *fw_dump_hdr = (struct nxp_fw_dump_hdr *)skb->data;
 	struct btnxpuart_dev *nxpdev = hci_get_drvdata(hdev);
 	__u16 seq_num;
 	__u16 buf_len;
 	int err;
 
-	fw_dump_hdr = skb_pull_data(skb, sizeof(*fw_dump_hdr));
-	if (!fw_dump_hdr) {
+	/* The ACL payload must be long enough to hold the FW dump header */
+	if (skb->len < sizeof(*fw_dump_hdr)) {
 		bt_dev_warn(hdev, "FW dump: invalid or corrupt fw dump chunk");
 		goto free_skb;
 	}
-- 
2.55.0