nfc: digital: Do not dump a NULL response in command completion

digital_wq_cmd_complete() dumps the response data whenever cmd->resp is
not an error pointer.  However, a driver can legitimately complete a
command with no response skb at all.

digital_tg_send_psl_res() is the only caller that passes timeout=0,
meaning no response is expected once the command has been transmitted.
On that path trf7970a completes the command with

	trf->rx_skb = ERR_PTR(0);

which evaluates to NULL.  IS_ERR(NULL) is false, so the NULL response
passes the !IS_ERR() check and cmd->resp->data and cmd->resp->len are
dereferenced whenever the debug print site is enabled.  The driver
guards its own dump with "trf->rx_skb && !IS_ERR(trf->rx_skb)"; the
digital layer is missing the NULL half of that test.

Use IS_ERR_OR_NULL() so that NULL responses are skipped as well.  The
callback on that path, digital_tg_send_psl_res_complete(), never
dereferences resp and dev_kfree_skb() accepts NULL, so only the debug
dump needs fixing.

Fixes: 59ee2361c924 ("NFC Digital: Implement driver commands mechanism")
Signed-off-by: Linmao Li <lilinmao@kylinos.cn>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/20260710061254.80975-1-lilinmao@kylinos.cn
Signed-off-by: David Heidelberg <david@ixit.cz>

0 files changed, 0 insertions, 0 deletions