linux-kernel - [PATCH] staging: rtl8188eu: Fix a possible sleep-in-atomic-context bug in rtw_disassoc

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Date:   Wed, 20 Jun 2018 18:01:19 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     gregkh@...uxfoundation.org, dan.carpenter@...cle.com,
        jananis37@...il.com
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] staging: rtl8188eu: Fix a possible sleep-in-atomic-context bug in rtw_disassoc_cmd()

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/rtl8188eu/core/rtw_cmd.c, 502: 
		kzalloc in rtw_disassoc_cmd
drivers/staging/rtl8188eu/core/rtw_ioctl_set.c, 256: 
		rtw_disassoc_cmd in rtw_set_802_11_ssid
drivers/staging/rtl8188eu/core/rtw_ioctl_set.c, 235: 
		spin_lock_bh in rtw_set_802_11_ssid

[FUNC] kzalloc(GFP_KERNEL)
drivers/staging/rtl8188eu/core/rtw_cmd.c, 502: 
		kzalloc in rtw_disassoc_cmd
drivers/staging/rtl8188eu/core/rtw_ioctl_set.c, 352: 
		rtw_disassoc_cmd in rtw_set_802_11_infrastructure_mode
drivers/staging/rtl8188eu/core/rtw_ioctl_set.c, 336: 
		spin_lock_bh in rtw_set_802_11_infrastructure_mode

To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/staging/rtl8188eu/core/rtw_cmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8188eu/core/rtw_cmd.c b/drivers/staging/rtl8188eu/core/rtw_cmd.c
index be8542676adf..f664fc935455 100644
--- a/drivers/staging/rtl8188eu/core/rtw_cmd.c
+++ b/drivers/staging/rtl8188eu/core/rtw_cmd.c
@@ -499,7 +499,7 @@ u8 rtw_disassoc_cmd(struct adapter *padapter, u32 deauth_timeout_ms, bool enqueu
 	RT_TRACE(_module_rtl871x_cmd_c_, _drv_notice_, ("+%s\n", __func__));
 
 	/* prepare cmd parameter */
-	param = kzalloc(sizeof(*param), GFP_KERNEL);
+	param = kzalloc(sizeof(*param), GFP_ATOMIC);
 	if (!param) {
 		res = _FAIL;
 		goto exit;
-- 
2.17.0