linux-kernel - [PATCH v3] staging: rtl8723bs: fix potential race in expire_timeout

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Message-ID: <20260129123342.309946-1-s9430939@naver.com>
Date: Thu, 29 Jan 2026 21:33:42 +0900
From: Minu Jin <s9430939@...er.com>
To: gregkh@...uxfoundation.org
Cc: dan.carpenter@...aro.org,
	bqn9090@...il.com,
	abrahamadekunle50@...il.com,
	straube.linux@...il.com,
	bryant.boatright@...ton.me,
	davidzalman.101@...il.com,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Minu Jin <s9430939@...er.com>
Subject: [PATCH v3] staging: rtl8723bs: fix potential race in expire_timeout_chk

The expire_timeout_chk function currently do lock and unlock inside the
loop before calling rtw_free_stainfo().

This can be risky as the list might be changed
when the lock is briefly released.

To fix this, move expired sta_info entries into a local free_list while
holding the lock, and then perform the actual freeing after the lock is
released.

Signed-off-by: Minu Jin <s9430939@...er.com>
---
Changes in v3:
    Suggested-by Dan Carpenter
    - Use list_for_each_entry_safe() only for the new code.
    - Remove blank line in the declaration block.
    - Keep existing code unchanged

 drivers/staging/rtl8723bs/core/rtw_ap.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_ap.c b/drivers/staging/rtl8723bs/core/rtw_ap.c
index 67197c7d4a4d..2ee7cc0ebaf6 100644
--- a/drivers/staging/rtl8723bs/core/rtw_ap.c
+++ b/drivers/staging/rtl8723bs/core/rtw_ap.c
@@ -178,6 +178,8 @@ void expire_timeout_chk(struct adapter *padapter)
 	struct sta_priv *pstapriv = &padapter->stapriv;
 	u8 chk_alive_num = 0;
 	char chk_alive_list[NUM_STA];
+	struct sta_info *psta_tmp;
+	LIST_HEAD(free_list);
 	int i;
 
 	spin_lock_bh(&pstapriv->auth_list_lock);
@@ -190,19 +192,19 @@ void expire_timeout_chk(struct adapter *padapter)
 		if (psta->expire_to > 0) {
 			psta->expire_to--;
 			if (psta->expire_to == 0) {
-				list_del_init(&psta->auth_list);
+				list_move(&psta->auth_list, &free_list);
 				pstapriv->auth_list_cnt--;
-
-				spin_unlock_bh(&pstapriv->auth_list_lock);
-
-				rtw_free_stainfo(padapter, psta);
-
-				spin_lock_bh(&pstapriv->auth_list_lock);
 			}
 		}
 	}
 
 	spin_unlock_bh(&pstapriv->auth_list_lock);
+
+	list_for_each_entry_safe(psta, psta_tmp, &free_list, auth_list) {
+		list_del_init(&psta->auth_list);
+		rtw_free_stainfo(padapter, psta);
+	}
+
 	psta = NULL;
 
 	spin_lock_bh(&pstapriv->asoc_list_lock);
-- 
2.43.0