KMSAN: uninit-value in nf_log_trace

Status: closed as invalid on 2026/09/11 15:35
Subsystems: netfilter
Labels: prio:high
[Documentation on labels]
First crash: 124d, last: 110d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
05518e3a assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ KMSAN: uninit-value in nf_log_trace 2026/06/02 08:57 2026/06/02 08:57 2026/06/02 10:05 1095583b

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in vsnprintf+0x15be/0x1b00 lib/vsprintf.c:2912
 vsnprintf+0x15be/0x1b00 lib/vsprintf.c:2912
 nf_log_trace+0x232/0x2c0 net/netfilter/nf_log.c:282
 trace_packet+0x5ca/0x770 net/ipv4/netfilter/ip_tables.c:209
 ipt_do_table+0x1a62/0x2150 net/ipv4/netfilter/ip_tables.c:306
 iptable_mangle_hook+0x429/0x670 net/ipv4/netfilter/iptable_mangle.c:80
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xe1/0x3d0 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK include/linux/netfilter.h:316 [inline]
 ip_local_deliver+0x39d/0x4a0 net/ipv4/ip_input.c:262
 dst_input include/net/dst.h:480 [inline]
 ip_rcv_finish+0x4d7/0x560 net/ipv4/ip_input.c:492
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip_rcv+0xcb/0x370 net/ipv4/ip_input.c:612
 __netif_receive_skb_one_core net/core/dev.c:6202 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0x8d7/0x1500 net/core/dev.c:6666
 __napi_poll+0xdc/0x910 net/core/dev.c:7733
 napi_poll net/core/dev.c:7796 [inline]
 net_rx_action+0xa5b/0x1c70 net/core/dev.c:7953
 handle_softirqs+0x171/0x7b0 kernel/softirq.c:622
 __do_softirq+0x14/0x1b kernel/softirq.c:656
 do_softirq+0x58/0x90 kernel/softirq.c:523
 __local_bh_enable_ip+0xa1/0xb0 kernel/softirq.c:450
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:196 [inline]
 _raw_spin_unlock_bh+0x2d/0x40 kernel/locking/spinlock.c:214
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 cfg80211_put_bss+0x2cc/0x3b0 net/wireless/scan.c:3356
 ieee80211_rx_bss_put+0x4c/0x70 net/mac80211/scan.c:37
 ieee80211_rx_bss_info net/mac80211/ibss.c:1160 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1569 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x204d/0x3f80 net/mac80211/ibss.c:1596
 ieee80211_iface_process_skb net/mac80211/iface.c:1795 [inline]
 ieee80211_iface_work+0x10f4/0x2010 net/mac80211/iface.c:1849
 cfg80211_wiphy_work+0x354/0x850 net/wireless/core.c:513
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3397
 worker_thread+0xee4/0x1590 kernel/workqueue.c:3478
 kthread+0x53a/0x5f0 kernel/kthread.c:436
 ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
 vsnprintf+0x15b7/0x1b00 lib/vsprintf.c:-1
 nf_log_trace+0x232/0x2c0 net/netfilter/nf_log.c:282
 trace_packet+0x5ca/0x770 net/ipv4/netfilter/ip_tables.c:209
 ipt_do_table+0x1a62/0x2150 net/ipv4/netfilter/ip_tables.c:306
 iptable_mangle_hook+0x429/0x670 net/ipv4/netfilter/iptable_mangle.c:80
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xe1/0x3d0 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK include/linux/netfilter.h:316 [inline]
 ip_local_deliver+0x39d/0x4a0 net/ipv4/ip_input.c:262
 dst_input include/net/dst.h:480 [inline]
 ip_rcv_finish+0x4d7/0x560 net/ipv4/ip_input.c:492
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip_rcv+0xcb/0x370 net/ipv4/ip_input.c:612
 __netif_receive_skb_one_core net/core/dev.c:6202 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0x8d7/0x1500 net/core/dev.c:6666
 __napi_poll+0xdc/0x910 net/core/dev.c:7733
 napi_poll net/core/dev.c:7796 [inline]
 net_rx_action+0xa5b/0x1c70 net/core/dev.c:7953
 handle_softirqs+0x171/0x7b0 kernel/softirq.c:622
 __do_softirq+0x14/0x1b kernel/softirq.c:656

Local variable prefix created at:
 nf_log_trace+0xee/0x2c0 net/netfilter/nf_log.c:275
 trace_packet+0x5ca/0x770 net/ipv4/netfilter/ip_tables.c:209

CPU: 1 UID: 0 PID: 18501 Comm: kworker/u8:32 Tainted: G             L      syzkaller #0 PREEMPT(lazy) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound cfg80211_wiphy_work
=====================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/05 18:08 upstream ddd664bbff63 48b6c3fa .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in nf_log_trace
2026/05/23 01:59 upstream 45255ea1ca09 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in nf_log_trace
* Struck through repros no longer work on HEAD.