linux-kernel - Re: [syzbot] [net?] possible deadlock in sch_direct

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 26 Nov 2023 01:46:46 -0800
From:   syzbot <syzbot+e18ac85757292b7baf96@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org
Subject: Re: [syzbot] [net?] possible deadlock in sch_direct_xmit

For archival purposes, forwarding an incoming command email to
linux-kernel@...r.kernel.org.

***

Subject: [net?] possible deadlock in sch_direct_xmit
Author: eadavis@...com

please test deadlock in sch_direct_xmit

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 4195a4bc26ca..d9d39887a550 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -337,13 +337,16 @@ bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 #endif
 
 	if (likely(skb)) {
-		HARD_TX_LOCK(dev, txq, smp_processor_id());
-		if (!netif_xmit_frozen_or_stopped(txq))
+		if (!netif_xmit_frozen_or_stopped(txq)) {
+			HARD_TX_LOCK(dev, txq, smp_processor_id());
+			netif_tx_stop_queue(txq);
 			skb = dev_hard_start_xmit(skb, dev, txq, &ret);
+			netif_tx_start_queue(txq);
+			HARD_TX_UNLOCK(dev, txq);
+		}
 		else
 			qdisc_maybe_clear_missed(q, txq);
 
-		HARD_TX_UNLOCK(dev, txq);
 	} else {
 		if (root_lock)
 			spin_lock(root_lock);