linux-kernel - [PATCH] mac80211_hwsim: Fix a possible sleep-in-atomic bug in hwsim_get_radio

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Date:   Tue, 12 Dec 2017 17:26:36 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     johannes@...solutions.net, kvalo@...eaurora.org, j@...fi,
        jlopex@...il.com
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] mac80211_hwsim: Fix a possible sleep-in-atomic bug in hwsim_get_radio_nl

The driver may sleep under a spinlock.
The function call path is:
hwsim_get_radio_nl (acquire the spinlock)
  nlmsg_new(GFP_KERNEL) --> may sleep

To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
---
 drivers/net/wireless/mac80211_hwsim.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 10b075a..f2ebf4a 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -3215,7 +3215,7 @@ static int hwsim_get_radio_nl(struct sk_buff *msg, struct genl_info *info)
 		if (!net_eq(wiphy_net(data->hw->wiphy), genl_info_net(info)))
 			continue;
 
-		skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+		skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 		if (!skb) {
 			res = -ENOMEM;
 			goto out_err;
-- 
1.7.9.5