==================================================================
BUG: KASAN: use-after-free in fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193
Read of size 8 at addr ffff888150088000 by task kworker/u4:3/302
CPU: 1 PID: 302 Comm: kworker/u4:3 Tainted: G W 5.10.238-syzkaller-00282-gd76d4cd0623a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:77
dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:435 [inline]
kasan_report+0xe2/0x130 mm/kasan/report.c:452
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193
__remove_nexthop_fib+0xab/0x260 net/ipv4/nexthop.c:879
__remove_nexthop net/ipv4/nexthop.c:893 [inline]
remove_nexthop+0x75/0x4d0 net/ipv4/nexthop.c:919
remove_nh_grp_entry net/ipv4/nexthop.c:797 [inline]
remove_nexthop_from_groups+0x193/0xe40 net/ipv4/nexthop.c:846
__remove_nexthop net/ipv4/nexthop.c:904 [inline]
remove_nexthop+0x38a/0x4d0 net/ipv4/nexthop.c:919
flush_all_nexthops net/ipv4/nexthop.c:1237 [inline]
nexthop_net_exit+0x3a/0xa0 net/ipv4/nexthop.c:2012
ops_exit_list net/core/net_namespace.c:185 [inline]
cleanup_net+0x586/0xb70 net/core/net_namespace.c:609
process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
kthread+0x346/0x3d0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Allocated by task 25963:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:430 [inline]
____kasan_kmalloc mm/kasan/common.c:509 [inline]
__kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518
kasan_kmalloc include/linux/kasan.h:254 [inline]
kmem_cache_alloc_trace+0x184/0x2e0 mm/slub.c:2974
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:664 [inline]
ip_fib_net_init net/ipv4/fib_frontend.c:1547 [inline]
fib_net_init+0xe0/0x2c0 net/ipv4/fib_frontend.c:1606
ops_init+0x1ba/0x4a0 net/core/net_namespace.c:144
setup_net+0x36d/0xb50 net/core/net_namespace.c:345
copy_net_ns+0x314/0x520 net/core/net_namespace.c:486
create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231
ksys_unshare+0x4ac/0x7d0 kernel/fork.c:3156
__do_sys_unshare kernel/fork.c:3224 [inline]
__se_sys_unshare kernel/fork.c:3222 [inline]
__x64_sys_unshare+0x38/0x40 kernel/fork.c:3222
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Freed by task 302:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
kasan_slab_free include/linux/kasan.h:220 [inline]
slab_free_hook mm/slub.c:1595 [inline]
slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1621
slab_free mm/slub.c:3203 [inline]
kfree+0xc0/0x270 mm/slub.c:4191
ip_fib_net_exit+0x32f/0x350 net/ipv4/fib_frontend.c:1595
fib_net_exit+0x6c/0x80 net/ipv4/fib_frontend.c:1629
ops_exit_list net/core/net_namespace.c:185 [inline]
cleanup_net+0x586/0xb70 net/core/net_namespace.c:609
process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
kthread+0x346/0x3d0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
__call_rcu kernel/rcu/tree.c:2976 [inline]
call_rcu+0x105/0x1040 kernel/rcu/tree.c:3050
netlink_release+0x1288/0x1690 net/netlink/af_netlink.c:796
__sock_release net/socket.c:597 [inline]
sock_close+0xe0/0x270 net/socket.c:1286
__fput+0x2fb/0x770 fs/file_table.c:281
____fput+0x15/0x20 fs/file_table.c:314
task_work_run+0x127/0x190 kernel/task_work.c:189
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
exit_to_user_mode_prepare kernel/entry/common.c:199 [inline]
syscall_exit_to_user_mode+0x68/0x90 kernel/entry/common.c:274
do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Second to last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
insert_work+0x52/0x310 kernel/workqueue.c:1352
__queue_work+0x923/0xca0 kernel/workqueue.c:1518
__queue_delayed_work+0x188/0x200 kernel/workqueue.c:1672
mod_delayed_work_on+0x7b/0xd0 kernel/workqueue.c:1746
mod_delayed_work include/linux/workqueue.h:545 [inline]
wb_shutdown+0x164/0x1b0 mm/backing-dev.c:351
bdi_unregister+0x15e/0x4f0 mm/backing-dev.c:880
del_gendisk+0x479/0x9e0 block/genhd.c:929
loop_remove+0x46/0xb0 drivers/block/loop.c:2210
loop_control_ioctl+0x487/0x550 drivers/block/loop.c:2309
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
The buggy address belongs to the object at ffff888150088000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 0 bytes inside of
2048-byte region [ffff888150088000, ffff888150088800)
The buggy address belongs to the page:
page:ffffea0005402200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x150088
head:ffffea0005402200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042d80
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 12488, ts 516366691264, free_ts 508351038269
set_page_owner include/linux/page_owner.h:35 [inline]
post_alloc_hook mm/page_alloc.c:2456 [inline]
prep_new_page+0x179/0x180 mm/page_alloc.c:2462
get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
__alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5357
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1808 [inline]
new_slab+0x84/0x3f0 mm/slub.c:1869
new_slab_objects mm/slub.c:2627 [inline]
___slab_alloc+0x2a6/0x450 mm/slub.c:2791
__slab_alloc+0x63/0xa0 mm/slub.c:2831
slab_alloc_node mm/slub.c:2913 [inline]
slab_alloc mm/slub.c:2955 [inline]
__kmalloc_track_caller+0x1ef/0x320 mm/slub.c:4536
__kmalloc_reserve net/core/skbuff.c:144 [inline]
__alloc_skb+0xdc/0x520 net/core/skbuff.c:212
alloc_skb include/linux/skbuff.h:1126 [inline]
nlmsg_new include/net/netlink.h:953 [inline]
audit_buffer_alloc kernel/audit.c:1799 [inline]
audit_log_start+0x3df/0x860 kernel/audit.c:1917
audit_seccomp+0x62/0x160 kernel/auditsc.c:2675
seccomp_log kernel/seccomp.c:1004 [inline]
__seccomp_filter+0xb4c/0x1990 kernel/seccomp.c:1247
__secure_computing+0xea/0x290 kernel/seccomp.c:1313
syscall_trace_enter+0xb5/0x170 kernel/entry/common.c:58
__syscall_enter_from_user_work kernel/entry/common.c:81 [inline]
syscall_enter_from_user_mode+0x20/0x30 kernel/entry/common.c:99
do_syscall_64+0x13/0x40 arch/x86/entry/common.c:41
entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1349 [inline]
__free_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629
free_the_page mm/page_alloc.c:5418 [inline]
__free_pages+0xdd/0x380 mm/page_alloc.c:5427
__free_slab+0xcf/0x190 mm/slub.c:1894
free_slab mm/slub.c:1909 [inline]
discard_slab mm/slub.c:1915 [inline]
unfreeze_partials+0x15f/0x190 mm/slub.c:2410
put_cpu_partial+0xc1/0x180 mm/slub.c:2446
__slab_free+0x2c9/0x3a0 mm/slub.c:3095
do_slab_free mm/slub.c:3191 [inline]
___cache_free+0x111/0x130 mm/slub.c:3210
qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
kasan_slab_alloc include/linux/kasan.h:244 [inline]
slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:583
slab_alloc_node mm/slub.c:2947 [inline]
slab_alloc mm/slub.c:2955 [inline]
kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2960
getname_flags+0xb9/0x500 fs/namei.c:141
getname+0x19/0x20 fs/namei.c:212
do_sys_openat2+0xd9/0x6d0 fs/open.c:1211
Memory state around the buggy address:
ffff888150087f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888150087f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888150088000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888150088080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888150088100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
general protection fault, probably for non-canonical address 0xfef7fc2840000025: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xf7c0014200000128-0xf7c001420000012f]
CPU: 0 PID: 302 Comm: kworker/u4:3 Tainted: G B W 5.10.238-syzkaller-00282-gd76d4cd0623a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
RIP: 0010:fib_flush+0x96/0x120 net/ipv4/fib_frontend.c:193
Code: 00 74 08 4c 89 e7 e8 99 1c c4 fd 4d 8b 3c 24 4d 85 ff 75 0f e8 2b 2c 8a fd eb 3b e8 24 2c 8a fd 4d 89 e7 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 1c c4 fd 4d 8b 27 48 89 df 4c
RSP: 0018:ffffc900079e79d0 EFLAGS: 00010a03
RAX: 1ef8002840000025 RBX: ffff888110812680 RCX: 0000000000000286
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888150088008
RBP: ffffc900079e7a10 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: ffff888150088008
R13: dffffc0000000000 R14: 0000000000000000 R15: f7c001420000012e
FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f62838acf98 CR3: 0000000123feb000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__remove_nexthop_fib+0xab/0x260 net/ipv4/nexthop.c:879
__remove_nexthop net/ipv4/nexthop.c:893 [inline]
remove_nexthop+0x75/0x4d0 net/ipv4/nexthop.c:919
remove_nh_grp_entry net/ipv4/nexthop.c:797 [inline]
remove_nexthop_from_groups+0x193/0xe40 net/ipv4/nexthop.c:846
__remove_nexthop net/ipv4/nexthop.c:904 [inline]
remove_nexthop+0x38a/0x4d0 net/ipv4/nexthop.c:919
flush_all_nexthops net/ipv4/nexthop.c:1237 [inline]
nexthop_net_exit+0x3a/0xa0 net/ipv4/nexthop.c:2012
ops_exit_list net/core/net_namespace.c:185 [inline]
cleanup_net+0x586/0xb70 net/core/net_namespace.c:609
process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
kthread+0x346/0x3d0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace 90baa47f4bc1d019 ]---
RIP: 0010:fib_flush+0x96/0x120 net/ipv4/fib_frontend.c:193
Code: 00 74 08 4c 89 e7 e8 99 1c c4 fd 4d 8b 3c 24 4d 85 ff 75 0f e8 2b 2c 8a fd eb 3b e8 24 2c 8a fd 4d 89 e7 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 1c c4 fd 4d 8b 27 48 89 df 4c
RSP: 0018:ffffc900079e79d0 EFLAGS: 00010a03
RAX: 1ef8002840000025 RBX: ffff888110812680 RCX: 0000000000000286
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888150088008
RBP: ffffc900079e7a10 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: ffff888150088008
R13: dffffc0000000000 R14: 0000000000000000 R15: f7c001420000012e
FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f62838acf98 CR3: 000000012a16e000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 74 08 4c add %dh,0x4c(%rax,%rcx,1)
4: 89 e7 mov %esp,%edi
6: e8 99 1c c4 fd call 0xfdc41ca4
b: 4d 8b 3c 24 mov (%r12),%r15
f: 4d 85 ff test %r15,%r15
12: 75 0f jne 0x23
14: e8 2b 2c 8a fd call 0xfd8a2c44
19: eb 3b jmp 0x56
1b: e8 24 2c 8a fd call 0xfd8a2c44
20: 4d 89 e7 mov %r12,%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi
34: e8 6b 1c c4 fd call 0xfdc41ca4
39: 4d 8b 27 mov (%r15),%r12
3c: 48 89 df mov %rbx,%rdi
3f: 4c rex.WR