* [syzbot] [net?] KASAN: null-ptr-deref Read in netlink_has_listeners
@ 2026-10-26 18:43 syzbot
2026-10-26 21:15 ` Fernando Fernandez Mancera
0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2026-10-26 18:43 UTC (permalink / raw)
To: linux-kernel, netdev, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: c03c1a14507d Linux 7.3
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=13a01ae1580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4ccb65e03706547e
dashboard link: https://syzkaller.appspot.com/bug?extid=1269fe6cc2016008124e
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11515031580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1269fe6cc2016008124e@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: null-ptr-deref in netlink_is_kernel net/netlink/af_netlink.c:88 [inline]
BUG: KASAN: null-ptr-deref in netlink_has_listeners+0x3d/0x3f0 net/netlink/af_netlink.c:1390
Read of size 8 at addr 0000000000000578 by task syz-executor333/5617
CPU: 0 UID: 0 PID: 5617 Comm: syz-executor333 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
kasan_report+0x117/0x150 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
instrument_atomic_read include/linux/instrumented.h:82 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
netlink_is_kernel net/netlink/af_netlink.c:88 [inline]
netlink_has_listeners+0x3d/0x3f0 net/netlink/af_netlink.c:1390
genl_has_listeners include/net/genetlink.h:644 [inline]
devlink_nl_notify_need net/devlink/devl_internal.h:238 [inline]
devlink_port_notify+0x18c/0x520 net/devlink/port.c:559
__devlink_port_type_set+0x5f1/0x7a0 net/devlink/port.c:1237
devlink_port_netdevice_event+0x25d/0x3a0 net/devlink/port.c:-1
notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2313 [inline]
call_netdevice_notifiers net/core/dev.c:2327 [inline]
unregister_netdevice_many_notify+0x1a76/0x2140 net/core/dev.c:12580
unregister_netdevice_many net/core/dev.c:12635 [inline]
unregister_netdevice_queue+0x2f5/0x340 net/core/dev.c:12436
unregister_netdevice include/linux/netdevice.h:3490 [inline]
nsim_destroy+0x275/0x800 drivers/net/netdevsim/netdev.c:1198
__nsim_dev_port_del+0x14e/0x200 drivers/net/netdevsim/dev.c:1472
nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1486 [inline]
nsim_dev_reload_destroy+0x288/0x490 drivers/net/netdevsim/dev.c:1710
nsim_drv_remove+0x58/0x170 drivers/net/netdevsim/dev.c:1725
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
bus_remove_device+0x444/0x560 drivers/base/bus.c:664
device_del+0x524/0x8f0 drivers/base/core.c:3965
device_unregister+0x21/0xf0 drivers/base/core.c:4006
nsim_bus_dev_del drivers/net/netdevsim/bus.c:488 [inline]
del_device_store+0x2b5/0x370 drivers/net/netdevsim/bus.c:244
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb10e25df77
Code: 48 89 fa 4c 89 df e8 98 1e 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd1f1777c0 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000555587f6f400 RCX: 00007fb10e25df77
RDX: 0000000000000003 RSI: 00007fb10e29d08b RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd1f177938
R13: 0000000000000002 R14: 00007fb10e2c5c80 R15: 0000000000000002
</TASK>
==================================================================
---
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2026-10-26 18:43 [syzbot] [net?] KASAN: null-ptr-deref Read in netlink_has_listeners syzbot
2026-10-26 21:15 ` Fernando Fernandez Mancera
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