Hi Sean,
> Fixed all the below warnings. They would probably cause the following
> error handling path would use the uninitialized value and then produce
> unexpected behavior.
>
> drivers/bluetooth/btmtksdio.c:470:2: warning: ‘old_len’ may be used
> uninitialized in this function [-Wmaybe-uninitialized]
> print_hex_dump(KERN_ERR, "err sdio rx: ", DUMP_PREFIX_NONE, 4, 1,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> old_data, old_len, true);
> ~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/bluetooth/btmtksdio.c:376:15: note: ‘old_len’ was declared here
> unsigned int old_len;
> ^~~~~~~
> drivers/bluetooth/btmtksdio.c:470:2: warning: ‘old_data’ may be used
> uninitialized in this function [-Wmaybe-uninitialized]
> print_hex_dump(KERN_ERR, "err sdio rx: ", DUMP_PREFIX_NONE, 4, 1,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> old_data, old_len, true);
> ~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/bluetooth/btmtksdio.c:375:17: note: ‘old_data’ was declared here
> unsigned char *old_data;
> ^~~~~~~~
>
> Fixes: d74eef2834b5 ("Bluetooth: mediatek: add support for MediaTek MT7663S and MT7668S SDIO devices")
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Reported-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> Signed-off-by: Sean Wang <sean.wang@xxxxxxxxxxxx>
> ---
> drivers/bluetooth/btmtksdio.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
> index b4b8320f279e..23cf63888bac 100644
> --- a/drivers/bluetooth/btmtksdio.c
> +++ b/drivers/bluetooth/btmtksdio.c
> @@ -372,8 +372,8 @@ static int btmtksdio_rx_packet(struct btmtksdio_dev *bdev, u16 rx_size)
> const struct h4_recv_pkt *pkts = mtk_recv_pkts;
> int pkts_count = ARRAY_SIZE(mtk_recv_pkts);
> struct mtkbtsdio_hdr *sdio_hdr;
> - unsigned char *old_data;
> - unsigned int old_len;
> + unsigned char *old_data = NULL;
> + unsigned int old_len = 0;
> int err, i, pad_size;
> struct sk_buff *skb;
> u16 dlen;
or instead just remove this whole old_len + old_data stuff anyway since it is rather pointless. Or at least introduce a proper error path for sdio_readsb since you know when it fails, there is no point in writing the SKB.
Regards
Marcel
