[PATCH] staging: rtl8723bs: Fix two possible sleep-in-atomic-context bugs in translate_scan()

[Jia-Ju Bai]

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

[FUNC] kzalloc(GFP_KERNEL)
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 323: 
		kzalloc in translate_scan
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1554: 
		translate_scan in rtw_wx_get_scan
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1533: 
		spin_lock_bh in rtw_wx_get_scan

[FUNC] kzalloc(GFP_KERNEL)
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 455: 
		kzalloc in translate_scan
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1554: 
		translate_scan in rtw_wx_get_scan
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1533: 
		spin_lock_bh in rtw_wx_get_scan

To fix these bugs, GFP_KERNEL is replaced with GFP_ATOMIC.

These bugs are found by my static analysis tool (DSAC-2) and checked by
my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
---
 drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
index b26533983864..7632b8974563 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -321,7 +321,7 @@ static char *translate_scan(struct adapter *padapter,
 		RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: ssid =%s\n", pnetwork->network.Ssid.Ssid));
 		RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: wpa_len =%d rsn_len =%d\n", wpa_len, rsn_len));
 
-		buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_KERNEL);
+		buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_ATOMIC);
 		if (!buf)
 			return start;
 		if (wpa_len > 0) {
@@ -453,7 +453,7 @@ static char *translate_scan(struct adapter *padapter,
 		u8 *buf;
 		u8 *p, *pos;
 
-		buf = kzalloc(MAX_WPA_IE_LEN, GFP_KERNEL);
+		buf = kzalloc(MAX_WPA_IE_LEN, GFP_ATOMIC);
 		if (!buf)
 			goto exit;
 		p = buf;
-- 
2.17.0