linux-kernel - [PATCH] crypto: chelsio: chtls: fix possible sleep-in-atomic-context bugs in abort_syn

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Date:   Wed, 18 Dec 2019 11:34:22 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     atul.gupta@...lsio.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, tglx@...utronix.de, allison@...utok.net,
        arjun@...lsio.com, kstewart@...uxfoundation.org,
        edumazet@...gle.com
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] crypto: chelsio: chtls: fix possible sleep-in-atomic-context bugs in abort_syn_rcv()

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/crypto/chelsio/chtls/chtls_cm.c, 1806: 
	alloc_skb(GFP_KERNEL) in send_abort_rpl
drivers/crypto/chelsio/chtls/chtls_cm.c, 1925: 
	send_abort_rpl in abort_syn_rcv
drivers/crypto/chelsio/chtls/chtls_cm.c, 1920: 
	spin_lock in abort_syn_rcv

drivers/crypto/chelsio/chtls/chtls_cm.c, 1787: 
	alloc_skb(GFP_KERNEL) in send_defer_abort_rpl
drivers/crypto/chelsio/chtls/chtls_cm.c, 1811: 
	send_defer_abort_rpl in send_abort_rpl
drivers/crypto/chelsio/chtls/chtls_cm.c, 1925: 
    send_abort_rpl in abort_syn_rcv
drivers/crypto/chelsio/chtls/chtls_cm.c, 1920: 
    spin_lock in abort_syn_rcv

alloc_skb(GFP_KERNEL) can sleep at runtime.

To fix these possible bugs, GFP_KERNEL is replaced with GFP_ATOMIC.
Besides, in send_defer_abort_rpl(), error handling code is added to 
handle the failure of alloc_skb().

These bugs are found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/crypto/chelsio/chtls/chtls_cm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/chelsio/chtls/chtls_cm.c b/drivers/crypto/chelsio/chtls/chtls_cm.c
index aca75237bbcf..e6e4c3ddc368 100644
--- a/drivers/crypto/chelsio/chtls/chtls_cm.c
+++ b/drivers/crypto/chelsio/chtls/chtls_cm.c
@@ -1805,8 +1805,11 @@ static void send_defer_abort_rpl(struct chtls_dev *cdev, struct sk_buff *skb)
 	struct cpl_abort_req_rss *req = cplhdr(skb);
 	struct sk_buff *reply_skb;
 
-	reply_skb = alloc_skb(sizeof(struct cpl_abort_rpl),
-			      GFP_KERNEL | __GFP_NOFAIL);
+	reply_skb = alloc_skb(sizeof(struct cpl_abort_rpl), GFP_ATOMIC);
+	if (!reply_skb) {
+		kfree_skb(skb);
+		return;
+	}
 	__skb_put(reply_skb, sizeof(struct cpl_abort_rpl));
 	set_abort_rpl_wr(reply_skb, GET_TID(req),
 			 (req->status & CPL_ABORT_NO_RST));
@@ -1825,7 +1828,7 @@ static void send_abort_rpl(struct sock *sk, struct sk_buff *skb,
 	csk = rcu_dereference_sk_user_data(sk);
 
 	reply_skb = alloc_skb(sizeof(struct cpl_abort_rpl),
-			      GFP_KERNEL);
+			      GFP_ATOMIC);
 
 	if (!reply_skb) {
 		req->status = (queue << 1);
-- 
2.17.1