================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline] BUG: KASAN: use-after-free in enqueue_timer+0xb7/0x300 kernel/time/timer.c:541 Write of size 8 at addr ffff8881e35cf1c8 by task syz-executor.2/2025 CPU: 1 PID: 2025 Comm: syz-executor.2 Tainted: G W 5.4.274-syzkaller-00002-g6f97bd951d82 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x241 lib/dump_stack.c:118 print_address_description+0x8c/0x600 mm/kasan/report.c:384 __kasan_report+0xf3/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 hlist_add_head include/linux/list.h:814 [inline] enqueue_timer+0xb7/0x300 kernel/time/timer.c:541 __internal_add_timer kernel/time/timer.c:554 [inline] internal_add_timer+0x240/0x430 kernel/time/timer.c:604 __mod_timer+0x6f1/0x13e0 kernel/time/timer.c:1065 call_timer_fn+0x36/0x390 kernel/time/timer.c:1448 expire_timers kernel/time/timer.c:1493 [inline] __run_timers+0x879/0xbe0 kernel/time/timer.c:1817 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1830 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x195/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:538 [inline] smp_apic_timer_interrupt+0x11a/0x460 arch/x86/kernel/apic/apic.c:1149 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834 RIP: 0010:inet6_rtm_newaddr+0x487/0x2750 net/ipv6/addrconf.c:4851 Code: ff ff ff 48 8d 84 24 e0 02 00 00 48 8d 78 30 48 89 f8 48 c1 e8 03 42 80 3c 30 00 74 05 e8 e1 d4 bf fd 48 8b 9c 24 10 03 00 00 <48> 85 db 74 75 e8 bf ef 8f fd 4c 8d 7b 08 4c 89 f8 48 c1 e8 03 42 RSP: 0018:ffff8881e2b2f220 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff1103c565ea6 RBX: 0000000000000000 RCX: 1ffff1103c565eb4 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8881e2b2f530 RBP: ffff8881e2b2f630 R08: ffffffff83d44a43 R09: ffff8881e2b2f588 R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff1103c565e58 R13: ffff8881ea4d3c1c R14: dffffc0000000000 R15: ffff8881e2b2f580 rtnetlink_rcv_msg+0x983/0xc70 net/core/rtnetlink.c:5290 netlink_rcv_skb+0x1d5/0x420 net/netlink/af_netlink.c:2481 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0x936/0xb20 net/netlink/af_netlink.c:1347 netlink_sendmsg+0xa18/0xcf0 net/netlink/af_netlink.c:1915 sock_sendmsg_nosec net/socket.c:638 [inline] __sock_sendmsg net/socket.c:650 [inline] __sys_sendto+0x4f3/0x6c0 net/socket.c:1961 __do_sys_sendto net/socket.c:1973 [inline] __se_sys_sendto net/socket.c:1969 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:1969 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7f8635c7bd43 Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 80 3d c1 91 10 00 00 41 89 ca 74 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 55 48 83 ec 30 44 89 4c 24 RSP: 002b:00007fff51cbc468 EFLAGS: 00000202 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f86368e1620 RCX: 00007f8635c7bd43 RDX: 0000000000000040 RSI: 00007f86368e1670 RDI: 0000000000000003 RBP: 0000000000000001 R08: 00007fff51cbc484 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003 R13: 0000000000000000 R14: 00007f86368e1670 R15: 0000000000000000 Allocated by task 1916: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x100/0x2b0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1080 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1193 [inline] netlink_sendmsg+0x797/0xcf0 net/netlink/af_netlink.c:1890 sock_sendmsg_nosec net/socket.c:638 [inline] __sock_sendmsg net/socket.c:650 [inline] __sys_sendto+0x4f3/0x6c0 net/socket.c:1961 __do_sys_sendto net/socket.c:1973 [inline] __se_sys_sendto net/socket.c:1969 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:1969 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 1916: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook mm/slub.c:1494 [inline] slab_free mm/slub.c:3080 [inline] kfree+0x123/0x370 mm/slub.c:4071 skb_release_all net/core/skbuff.c:675 [inline] __kfree_skb net/core/skbuff.c:689 [inline] consume_skb+0xa5/0x2a0 net/core/skbuff.c:849 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x93e/0xb20 net/netlink/af_netlink.c:1347 netlink_sendmsg+0xa18/0xcf0 net/netlink/af_netlink.c:1915 sock_sendmsg_nosec net/socket.c:638 [inline] __sock_sendmsg net/socket.c:650 [inline] __sys_sendto+0x4f3/0x6c0 net/socket.c:1961 __do_sys_sendto net/socket.c:1973 [inline] __se_sys_sendto net/socket.c:1969 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:1969 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 The buggy address belongs to the object at ffff8881e35cf000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 456 bytes inside of 512-byte region [ffff8881e35cf000, ffff8881e35cf200) The buggy address belongs to the page: page:ffffea00078d7300 refcount:1 mapcount:0 mapping:ffff8881f5c02500 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02500 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x18f/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893 alloc_slab_page+0x39/0x3c0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x97/0x440 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x2fe/0x490 mm/slub.c:2667 __slab_alloc+0x62/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x16d/0x2b0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1080 [inline] nlmsg_new include/net/netlink.h:888 [inline] netlink_ack+0x2cc/0xa70 net/netlink/af_netlink.c:2415 netlink_rcv_skb+0x252/0x420 net/netlink/af_netlink.c:2487 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0x936/0xb20 net/netlink/af_netlink.c:1347 netlink_sendmsg+0xa18/0xcf0 net/netlink/af_netlink.c:1915 sock_sendmsg_nosec net/socket.c:638 [inline] __sock_sendmsg net/socket.c:650 [inline] __sys_sendto+0x4f3/0x6c0 net/socket.c:1961 __do_sys_sendto net/socket.c:1973 [inline] __se_sys_sendto net/socket.c:1969 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:1969 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4955 [inline] __free_pages+0x91/0x140 mm/page_alloc.c:4961 device_release+0x6b/0x190 drivers/base/core.c:1776 kobject_cleanup lib/kobject.c:716 [inline] kobject_release lib/kobject.c:747 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e6/0x2f0 lib/kobject.c:764 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2919 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3182 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Memory state around the buggy address: ffff8881e35cf080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881e35cf100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881e35cf180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881e35cf200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881e35cf280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 0 P4D 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 1 PID: 2081 Comm: syz-executor.3 Tainted: G B W 5.4.274-syzkaller-00002-g6f97bd951d82 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: ff 48 8d decl -0x73(%rax) 3: 84 24 e0 test %ah,(%rax,%riz,8) 6: 02 00 add (%rax),%al 8: 00 48 8d add %cl,-0x73(%rax) b: 78 30 js 0x3d d: 48 89 f8 mov %rdi,%rax 10: 48 c1 e8 03 shr $0x3,%rax 14: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) 19: 74 05 je 0x20 1b: e8 e1 d4 bf fd call 0xfdbfd501 20: 48 8b 9c 24 10 03 00 mov 0x310(%rsp),%rbx 27: 00 * 28: 48 85 db test %rbx,%rbx <-- trapping instruction 2b: 74 75 je 0xa2 2d: e8 bf ef 8f fd call 0xfd8feff1 32: 4c 8d 7b 08 lea 0x8(%rbx),%r15 36: 4c 89 f8 mov %r15,%rax 39: 48 c1 e8 03 shr $0x3,%rax 3d: 42 rex.X