================================================================== BUG: KASAN: use-after-free in fib_flush+0x77/0x120 net/ipv4/fib_frontend.c:193 Read of size 8 at addr ffff888112a6f000 by task kworker/u4:2/48 CPU: 1 PID: 48 Comm: kworker/u4:2 Not tainted 5.10.238-syzkaller-00008-g59e9a7228857 #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 8181: 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 48: 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 ffff888112a6f000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 0 bytes inside of 2048-byte region [ffff888112a6f000, ffff888112a6f800) The buggy address belongs to the page: page:ffffea00044a9a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112a68 head:ffffea00044a9a00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 0000000000000000 0000000100000001 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 4642, ts 246619915007, free_ts 246616959207 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] __kmalloc+0x183/0x330 mm/slub.c:4029 kmalloc include/linux/slab.h:557 [inline] kernfs_file_read_iter fs/kernfs/file.c:195 [inline] kernfs_fop_read_iter+0x15d/0x470 fs/kernfs/file.c:242 call_read_iter include/linux/fs.h:2060 [inline] new_sync_read fs/read_write.c:415 [inline] vfs_read+0x874/0xa10 fs/read_write.c:496 ksys_read+0x140/0x240 fs/read_write.c:634 Memory state around the buggy address: ffff888112a6ef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888112a6ef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888112a6f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888112a6f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888112a6f100: 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: 1 PID: 48 Comm: kworker/u4:2 Tainted: G B 5.10.238-syzkaller-00008-g59e9a7228857 #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 d0 d5 c1 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 2d RSP: 0018:ffffc900009d7840 EFLAGS: 00010a03 RAX: 1d90690a6a882aa8 RBX: ec83485354415546 RCX: ffff888101df3b40 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900009d79c0 R08: 0000000000000004 R09: 0000000000000003 R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: dffffc0000000000 R13: 0000000000000001 R14: ffffffff83d6e3f0 R15: ffff88811c0b6000 FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f08258267f8 CR3: 000000000620f000 CR4: 00000000003506a0 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 eef866f6f27544d3 ]--- 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 d0 d5 c1 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 2d RSP: 0018:ffffc900009d7840 EFLAGS: 00010a03 RAX: 1d90690a6a882aa8 RBX: ec83485354415546 RCX: ffff888101df3b40 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900009d79c0 R08: 0000000000000004 R09: 0000000000000003 R10: fffffbfff0d8e448 R11: 1ffffffff0d8e448 R12: dffffc0000000000 R13: 0000000000000001 R14: ffffffff83d6e3f0 R15: ffff88811c0b6000 FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f89ccfc2ab8 CR3: 000000010d9d4000 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 d0 d5 c1 fd call 0xfdc1d5e0 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: 2d .byte 0x2d