==================================================================
BUG: KASAN: use-after-free in fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193
Read of size 8 at addr ffff888124812000 by task kworker/u4:4/469
CPU: 0 PID: 469 Comm: kworker/u4:4 Not tainted 5.10.240-syzkaller-00213-gad9a98ef27a4 #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 276:
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 469:
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
The buggy address belongs to the object at ffff888124812000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 0 bytes inside of
2048-byte region [ffff888124812000, ffff888124812800)
The buggy address belongs to the page:
page:ffffea0004920400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x124810
head:ffffea0004920400 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 276, ts 25183036444, free_ts 0
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+0x201/0x330 mm/slub.c:4029
kmalloc include/linux/slab.h:557 [inline]
sk_prot_alloc+0xb2/0x340 net/core/sock.c:1716
sk_alloc+0x38/0x4e0 net/core/sock.c:1774
__netlink_create net/netlink/af_netlink.c:621 [inline]
__netlink_kernel_create+0x186/0x940 net/netlink/af_netlink.c:2040
netlink_kernel_create include/linux/netlink.h:60 [inline]
uevent_net_init+0xe1/0x2b0 lib/kobject_uevent.c:785
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
page_owner free stack trace missing
Memory state around the buggy address:
ffff888124811f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888124811f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888124812000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888124812080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888124812100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
general protection fault, probably for non-canonical address 0xfd90650a6a882aa8: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xec83485354415540-0xec83485354415547]
CPU: 0 PID: 469 Comm: kworker/u4:4 Tainted: G B 5.10.240-syzkaller-00213-gad9a98ef27a4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
RIP: 0010:fib_table_flush+0x31a/0x1330 net/ipv4/fib_trie.c:1992
Code: 38 c1 0f 8c 71 ff ff ff 48 89 df e8 50 aa c0 fd e9 64 ff ff ff 4c 89 6c 24 38 48 89 44 24 20 48 8d 58 05 48 89 d8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 99 0d 00 00 0f b6 1b 31 ff 89 de e8 ed
RSP: 0018:ffffc90000d97840 EFLAGS: 00010a03
RAX: 1d90690a6a882aa8 RBX: ec83485354415546 RCX: ffff88811450a780
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000d979c0 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8e848 R11: 1ffffffff0d8e848 R12: dffffc0000000000
R13: 0000000000000001 R14: ffffffff83d81b90 R15: ffff88811dd6c000
FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010d104000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
fib_flush+0xb5/0x120 net/ipv4/fib_frontend.c:194
__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 d3ba80ce618755e5 ]---
RIP: 0010:fib_table_flush+0x31a/0x1330 net/ipv4/fib_trie.c:1992
Code: 38 c1 0f 8c 71 ff ff ff 48 89 df e8 50 aa c0 fd e9 64 ff ff ff 4c 89 6c 24 38 48 89 44 24 20 48 8d 58 05 48 89 d8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 99 0d 00 00 0f b6 1b 31 ff 89 de e8 ed
RSP: 0018:ffffc90000d97840 EFLAGS: 00010a03
RAX: 1d90690a6a882aa8 RBX: ec83485354415546 RCX: ffff88811450a780
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000d979c0 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8e848 R11: 1ffffffff0d8e848 R12: dffffc0000000000
R13: 0000000000000001 R14: ffffffff83d81b90 R15: ffff88811dd6c000
FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000620f000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 38 c1 cmp %al,%cl
2: 0f 8c 71 ff ff ff jl 0xffffff79
8: 48 89 df mov %rbx,%rdi
b: e8 50 aa c0 fd call 0xfdc0aa60
10: e9 64 ff ff ff jmp 0xffffff79
15: 4c 89 6c 24 38 mov %r13,0x38(%rsp)
1a: 48 89 44 24 20 mov %rax,0x20(%rsp)
1f: 48 8d 58 05 lea 0x5(%rax),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 99 0d 00 00 jne 0xdd0
37: 0f b6 1b movzbl (%rbx),%ebx
3a: 31 ff xor %edi,%edi
3c: 89 de mov %ebx,%esi
3e: e8 .byte 0xe8
3f: ed in (%dx),%eax