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From:   Jia-Ju Bai <baijiaju1990@gmail.com>
To:     isdn@linux-pingi.de
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH] isdn: mISDN: tei: Fix a sleep-in-atomic-context bug in create_teimgr()
Date:   Sat,  1 Sep 2018 20:00:19 +0800
Message-Id: <20180901120019.31664-1-baijiaju1990@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The kernel module may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] kzalloc(GFP_KERNEL)
drivers/isdn/mISDN/tei.c, 1058: kzalloc in create_teimgr
drivers/isdn/mISDN/tei.c, 1278: create_teimgr in mgr_ctrl
drivers/isdn/mISDN/tei.c, 1048: [FUNC_PTR]mgr_ctrl in create_teimgr
drivers/isdn/mISDN/tei.c, 1045: _raw_read_lock_irqsave in create_teimgr

Note that [FUNC_PTR] means a function pointer call is used.

To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.

This bug is found by my static analysis tool DSAC.

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

diff --git a/drivers/isdn/mISDN/tei.c b/drivers/isdn/mISDN/tei.c
index 12d9e5f4beb1..6d95ee639fdb 100644
--- a/drivers/isdn/mISDN/tei.c
+++ b/drivers/isdn/mISDN/tei.c
@@ -1055,7 +1055,7 @@ create_teimgr(struct manager *mgr, struct channel_req *crq)
 		       crq->adr.tei, crq->adr.sapi);
 	if (!l2)
 		return -ENOMEM;
-	l2->tm = kzalloc(sizeof(struct teimgr), GFP_KERNEL);
+	l2->tm = kzalloc(sizeof(struct teimgr), GFP_ATOMIC);
 	if (!l2->tm) {
 		kfree(l2);
 		printk(KERN_ERR "kmalloc teimgr failed\n");
-- 
2.17.0