net/netfilter/nf_conntrack_core.c | 4 ++++ 1 file changed, 4 insertions(+)
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Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com
#syz test
From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched
in
gc_worker
Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.
Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
net/netfilter/nf_conntrack_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_conntrack_core.c
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
break;
}
+ int entry_count = 0;
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
+ entry_count++;
+ if (entry_count > 100) break;
+ cond_resched();
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
--
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched
in
gc_worker
Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.
Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
net/netfilter/nf_conntrack_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_conntrack_core.c
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
break;
}
+ int entry_count = 0;
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
+ entry_count++;
+ if (entry_count > 100) break;
+ cond_resched();
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
--
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched
in
gc_worker
Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.
Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
net/netfilter/nf_conntrack_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_conntrack_core.c
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
break;
}
+ int entry_count = 0;
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
+ entry_count++;
+ if (entry_count > 100) break;
+ cond_resched();
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
--
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched
in
gc_worker
Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.
Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
net/netfilter/nf_conntrack_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_conntrack_core.c
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
break;
}
+ int entry_count = 0;
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
+ entry_count++;
+ if (entry_count > 100) break;
+ cond_resched();
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
--
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched
in
gc_worker
Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.
Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
net/netfilter/nf_conntrack_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/netfilter/nf_conntrack_core.c
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
break;
}
+ int entry_count = 0;
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
+ entry_count++;
+ if (entry_count > 100) break;
+ cond_resched();
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
--
2.43.0
On Monday, 19 January 2026 at 04:50:05 UTC+5:30 syzbot wrote:
Hello,
syzbot tried to test the proposed patch but the build/boot failed:
net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return'
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}'
token
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function
returning non-void [-Werror=return-type]
Tested on:
commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for
Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=100fdb9a580000© 2016 - 2026 Red Hat, Inc.