syzbot
KASAN: slab-use-after-free Read in ipvlan_hard_header (5)
Status:
upstream: reported on 2026/08/04 15:49
Subsystems:
net
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+1f9fd0f4b601cf88d6e6@syzkaller.appspotmail.com
First crash: 7d17h, last: 7d17h
Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in dev_hard_header include/linux/netdevice.h:3500 [inline]
BUG: KASAN: slab-use-after-free in ipvlan_hard_header+0xa2/0x120 drivers/net/ipvlan/ipvlan_main.c:385
Read of size 8 at addr ffff888033c58010 by task syz.1.5338/25164
CPU: 0 UID: 0 PID: 25164 Comm: syz.1.5338 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<IRQ>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
dev_hard_header include/linux/netdevice.h:3500 [inline]
ipvlan_hard_header+0xa2/0x120 drivers/net/ipvlan/ipvlan_main.c:385
dev_hard_header include/linux/netdevice.h:3503 [inline]
tipc_l2_send_msg+0x319/0x400 net/tipc/bearer.c:515
tipc_bearer_xmit_skb+0x2b3/0x400 net/tipc/bearer.c:576
tipc_disc_timeout+0x5f6/0x750 net/tipc/discover.c:340
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x225/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x30/0x90 kernel/kcov.c:314
Code: 04 24 65 48 8b 15 b8 07 a6 11 65 8b 0d d9 07 a6 11 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 24 17 00 00 00 74 52 <8b> 8a f8 16 00 00 83 f9 03 75 47 48 8b 8a 00 17 00 00 44 8b 8a fc
RSP: 0018:ffffc900064b75d8 EFLAGS: 00000246
RAX: ffffffff8219d998 RBX: ffffea0001693500 RCX: 0000000000000000
RDX: ffff88801de83e00 RSI: 0000000000000133 RDI: 0000000000000001
RBP: ffffc900064b78d0 R08: ffffea0001693507 R09: 1ffffd40002d26a0
R10: dffffc0000000000 R11: fffff940002d26a1 R12: 0000000000000000
R13: 800000005a4d4007 R14: ffff888026990668 R15: 0000000000000133
__zap_vma_range+0x1608/0x4f10 mm/memory.c:-1
unmap_vmas+0x390/0x550 mm/memory.c:2178
exit_mmap+0x293/0x9f0 mm/mmap.c:1300
__mmput+0x118/0x420 kernel/fork.c:1187
exit_mm+0x221/0x2d0 kernel/exit.c:615
do_exit+0x6cd/0x2360 kernel/exit.c:997
do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
__do_sys_exit_group kernel/exit.c:1163 [inline]
__se_sys_exit_group kernel/exit.c:1161 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1161
x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe52a99df99
Code: Unable to access opcode bytes at 0x7fe52a99df6f.
RSP: 002b:00007fe52ad4fd88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe52a99df99
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe52ad4fdec R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000001f6
R13: 00000000000927c0 R14: 0000000000166acd R15: 00007fe52ad4fe40
</TASK>
Allocated by task 16223:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5334 [inline]
__kvmalloc_node_noprof+0x53f/0x860 mm/slub.c:6905
alloc_netdev_mqs+0xa9/0x12b0 net/core/dev.c:12054
rtnl_create_link+0x321/0xd70 net/core/rtnetlink.c:3721
rtnl_newlink_create+0x25f/0xb00 net/core/rtnetlink.c:3903
__rtnl_newlink net/core/rtnetlink.c:4044 [inline]
rtnl_newlink+0x167f/0x1bd0 net/core/rtnetlink.c:4159
rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
__sys_sendto+0x408/0x5a0 net/socket.c:2252
__do_sys_sendto net/socket.c:2259 [inline]
__se_sys_sendto net/socket.c:2255 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2255
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 25158:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2677 [inline]
slab_free mm/slub.c:6377 [inline]
kfree+0x1c5/0x640 mm/slub.c:6692
device_release+0xc4/0x1f0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x222/0x550 lib/kobject.c:737
netdev_run_todo+0xf56/0x10d0 net/core/dev.c:11755
rtnl_unlock net/core/rtnetlink.c:157 [inline]
rtnl_net_unlock include/linux/rtnetlink.h:135 [inline]
rtnl_dellink+0x68f/0x810 net/core/rtnetlink.c:3651
rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888033c58000
which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 16 bytes inside of
freed 4096-byte region [ffff888033c58000, ffff888033c59000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33c58
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888033c59011
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b00a500 dead000000000100 dead000000000122
raw: 0000000000000000 0000200000040004 00000000f5000000 ffff888033c59011
head: 00fff00000000040 ffff88801b00a500 dead000000000100 dead000000000122
head: 0000000000000000 0000200000040004 00000000f5000000 ffff888033c59011
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5680, tgid 5680 (udevd), ts 133221374293, free_ts 133150703885
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab+0x79/0x5e0 mm/slub.c:3380
new_slab mm/slub.c:3426 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kvmalloc_node_noprof+0x66b/0x860 mm/slub.c:6905
seq_buf_alloc fs/seq_file.c:39 [inline]
seq_read_iter+0x1ea/0xca0 fs/seq_file.c:211
new_sync_read fs/read_write.c:493 [inline]
vfs_read+0x595/0xa80 fs/read_write.c:574
ksys_read+0x150/0x270 fs/read_write.c:716
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6255 tgid 6255 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5741
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_noprof+0x311/0x720 mm/slub.c:5359
_kmalloc_noprof include/linux/slab.h:992 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
__register_sysctl_table+0x6f/0x1370 fs/proc/proc_sysctl.c:1378
__addrconf_sysctl_register+0x31c/0x4b0 net/ipv6/addrconf.c:7366
addrconf_sysctl_register+0x168/0x1c0 net/ipv6/addrconf.c:7414
ipv6_add_dev+0xd26/0x13a0 net/ipv6/addrconf.c:460
addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3685
notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2288 [inline]
call_netdevice_notifiers net/core/dev.c:2302 [inline]
register_netdevice+0x18a4/0x1eb0 net/core/dev.c:11484
veth_newlink+0x49f/0xb70 drivers/net/veth.c:1863
rtnl_newlink_create+0x310/0xb00 net/core/rtnetlink.c:3913
__rtnl_newlink net/core/rtnetlink.c:4044 [inline]
rtnl_newlink+0x167f/0x1bd0 net/core/rtnetlink.c:4159
Memory state around the buggy address:
ffff888033c57f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888033c57f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888033c58000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888033c58080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888033c58100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 04 24 add $0x24,%al
2: 65 48 8b 15 b8 07 a6 mov %gs:0x11a607b8(%rip),%rdx # 0x11a607c2
9: 11
a: 65 8b 0d d9 07 a6 11 mov %gs:0x11a607d9(%rip),%ecx # 0x11a607ea
11: 81 e1 00 01 ff 00 and $0xff0100,%ecx
17: 74 11 je 0x2a
19: 81 f9 00 01 00 00 cmp $0x100,%ecx
1f: 75 5b jne 0x7c
21: 83 ba 24 17 00 00 00 cmpl $0x0,0x1724(%rdx)
28: 74 52 je 0x7c
* 2a: 8b 8a f8 16 00 00 mov 0x16f8(%rdx),%ecx <-- trapping instruction
30: 83 f9 03 cmp $0x3,%ecx
33: 75 47 jne 0x7c
35: 48 8b 8a 00 17 00 00 mov 0x1700(%rdx),%rcx
3c: 44 rex.R
3d: 8b .byte 0x8b
3e: 8a fc mov %ah,%bh
Struck through repros no longer work on HEAD.