staging: rtlwifi: Fix a possible sleep-in-atomic-context bug in _is_fw_read_cmd_down()

The driver may sleep with holding a spinlock.
The function call path (from bottom to top) in Linux-4.16.7 is:

[FUNC] schedule
drivers/staging/rtlwifi/halmac/rtl_halmac.c, 884:
		schedule in _is_fw_read_cmd_down
drivers/staging/rtlwifi/halmac/rtl_halmac.c, 912:
		_is_fw_read_cmd_down in rtl_halmac_send_h2c
drivers/staging/rtlwifi/halmac/rtl_halmac.c, 907:
		_raw_spin_lock_irqsave in rtl_halmac_send_h2c

To fix this bug, schedule() is replaced with mdelay(1).

This bug is found by my static analysis tool (DSAC-2) and checked by
my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/rtlwifi/halmac/rtl_halmac.c b/drivers/staging/rtlwifi/halmac/rtl_halmac.c
index ae433aa..f0c6fc8 100644 (file)
--- a/drivers/staging/rtlwifi/halmac/rtl_halmac.c
+++ b/drivers/staging/rtlwifi/halmac/rtl_halmac.c
@@ -870,7 +870,7 @@ static bool _is_fw_read_cmd_down(struct rtl_priv *rtlpriv, u8 msgbox_num)
                if (valid == 0)
                        read_down = true;
                else
-                       schedule();
+                       mdelay(1);
        } while ((!read_down) && (retry_cnts--));
 
        return read_down;