syzbot


KMSAN: uninit-value in ieee80211_radiotap_iterator_next

Status: upstream: reported on 2026/02/17 11:01
Subsystems: wireless
[Documentation on labels]
Reported-by: syzbot+b09c1af8764c0097bb19@syzkaller.appspotmail.com
First crash: 3d08h, last: 3d08h
Discussions (2)
Title Replies (including bot) Last reply
[PATCH wireless] wifi: radiotap: reject radiotap with unknown bits 1 (1) 2026/02/17 12:05
[syzbot] [wireless?] KMSAN: uninit-value in ieee80211_radiotap_iterator_next 0 (1) 2026/02/17 11:01

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in ieee80211_radiotap_iterator_next+0x11f8/0x1620 net/wireless/radiotap.c:317
 ieee80211_radiotap_iterator_next+0x11f8/0x1620 net/wireless/radiotap.c:317
 ieee80211_parse_tx_radiotap+0x4bb/0x2160 net/mac80211/tx.c:2122
 ieee80211_monitor_start_xmit+0x125e/0x1750 net/mac80211/tx.c:2451
 __netdev_start_xmit include/linux/netdevice.h:5275 [inline]
 netdev_start_xmit include/linux/netdevice.h:5284 [inline]
 xmit_one net/core/dev.c:3864 [inline]
 dev_hard_start_xmit+0x24e/0xad0 net/core/dev.c:3880
 __dev_queue_xmit+0x35e0/0x5a50 net/core/dev.c:4829
 dev_queue_xmit include/linux/netdevice.h:3384 [inline]
 packet_xmit+0x8f/0x710 net/packet/af_packet.c:275
 packet_snd net/packet/af_packet.c:3077 [inline]
 packet_sendmsg+0x91d9/0xa320 net/packet/af_packet.c:3109
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0xa77/0xb90 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __ia32_sys_sendto+0x12f/0x200 net/socket.c:2209
 ia32_sys_call+0x372f/0x4360 arch/x86/include/generated/asm/syscalls_32.h:370
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x17f/0x3f0 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x37/0x80 arch/x86/entry/syscall_32.c:332
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:370
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was stored to memory at:
 ieee80211_radiotap_iterator_next+0x14c8/0x1620 net/wireless/radiotap.c:251
 ieee80211_parse_tx_radiotap+0x4bb/0x2160 net/mac80211/tx.c:2122
 ieee80211_monitor_start_xmit+0x125e/0x1750 net/mac80211/tx.c:2451
 __netdev_start_xmit include/linux/netdevice.h:5275 [inline]
 netdev_start_xmit include/linux/netdevice.h:5284 [inline]
 xmit_one net/core/dev.c:3864 [inline]
 dev_hard_start_xmit+0x24e/0xad0 net/core/dev.c:3880
 __dev_queue_xmit+0x35e0/0x5a50 net/core/dev.c:4829
 dev_queue_xmit include/linux/netdevice.h:3384 [inline]
 packet_xmit+0x8f/0x710 net/packet/af_packet.c:275
 packet_snd net/packet/af_packet.c:3077 [inline]
 packet_sendmsg+0x91d9/0xa320 net/packet/af_packet.c:3109
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0xa77/0xb90 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __ia32_sys_sendto+0x12f/0x200 net/socket.c:2209
 ia32_sys_call+0x372f/0x4360 arch/x86/include/generated/asm/syscalls_32.h:370
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x17f/0x3f0 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x37/0x80 arch/x86/entry/syscall_32.c:332
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:370
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Local variable iterator created at:
 ieee80211_parse_tx_radiotap+0xc4/0x2160 net/mac80211/tx.c:2093
 ieee80211_monitor_start_xmit+0x125e/0x1750 net/mac80211/tx.c:2451

CPU: 1 UID: 0 PID: 12634 Comm: syz.4.1919 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/15 20:16 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in ieee80211_radiotap_iterator_next
2026/02/15 20:15 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in ieee80211_radiotap_iterator_next
2026/02/15 20:15 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in ieee80211_radiotap_iterator_next
* Struck through repros no longer work on HEAD.