================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline] BUG: KASAN: use-after-free in enqueue_timer+0x9e/0x2c0 kernel/time/timer.c:541 Write of size 8 at addr ffff8881d4eb71c8 by task syz.0.371/1711 CPU: 0 PID: 1711 Comm: syz.0.371 Not tainted 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack+0x1e/0x20 lib/dump_stack.c:77 dump_stack+0x15b/0x1b8 lib/dump_stack.c:118 print_address_description+0x8d/0x4c0 mm/kasan/report.c:384 __kasan_report+0xef/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:137 hlist_add_head include/linux/list.h:814 [inline] enqueue_timer+0x9e/0x2c0 kernel/time/timer.c:541 __internal_add_timer kernel/time/timer.c:554 [inline] internal_add_timer+0x208/0x3e0 kernel/time/timer.c:604 __mod_timer+0x5ab/0x1150 kernel/time/timer.c:1065 mod_timer+0x1f/0x30 kernel/time/timer.c:1117 can_stat_update+0xbab/0xc40 net/can/proc.c:186 call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448 expire_timers kernel/time/timer.c:1493 [inline] __run_timers+0x81d/0xb60 kernel/time/timer.c:1817 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830 __do_softirq+0x236/0x660 kernel/softirq.c:292 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1086 do_softirq+0xf9/0x140 kernel/softirq.c:337 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:189 local_bh_enable+0x1f/0x30 include/linux/bottom_half.h:32 rcu_read_unlock_bh include/linux/rcupdate.h:739 [inline] __dev_queue_xmit+0x136e/0x2400 net/core/dev.c:3848 dev_queue_xmit+0x17/0x20 net/core/dev.c:3854 __bpf_tx_skb net/core/filter.c:2063 [inline] __bpf_redirect_no_mac net/core/filter.c:2097 [inline] __bpf_redirect+0x699/0xe30 net/core/filter.c:2120 ____bpf_clone_redirect net/core/filter.c:2151 [inline] bpf_clone_redirect+0x242/0x380 net/core/filter.c:2123 bpf_prog_2658eab614f371a8+0x5c5/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x1ea/0x5d0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x721/0xdc0 net/bpf/test_run.c:311 bpf_prog_test_run+0x21a/0x2a0 kernel/bpf/syscall.c:2124 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x49a/0x570 kernel/bpf/syscall.c:2849 __x64_sys_bpf+0x7b/0x90 kernel/bpf/syscall.c:2849 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7fcb54afe969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fcb53167038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fcb54d25fa0 RCX: 00007fcb54afe969 RDX: 0000000000000050 RSI: 0000200000001300 RDI: 000000000000000a RBP: 00007fcb54b80ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fcb54d25fa0 R15: 00007fff9e21ee48 Allocated by task 1626: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x162/0x200 mm/kasan/common.c:529 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:537 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0xe2/0x270 mm/slub.c:2842 shmem_alloc_inode+0x1a/0x30 mm/shmem.c:3719 alloc_inode fs/inode.c:231 [inline] new_inode_pseudo+0x62/0x210 fs/inode.c:966 new_inode+0x28/0x1e0 fs/inode.c:995 shmem_get_inode+0x107/0x630 mm/shmem.c:2252 shmem_symlink+0x9e/0x4d0 mm/shmem.c:3068 vfs_symlink+0x337/0x4c0 fs/namei.c:4276 do_symlinkat+0x103/0x3b0 fs/namei.c:4303 __do_sys_symlinkat fs/namei.c:4317 [inline] __se_sys_symlinkat fs/namei.c:4314 [inline] __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 1652: 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+0x1c3/0x280 mm/kasan/common.c:487 kasan_slab_free+0xe/0x10 mm/kasan/common.c:496 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook+0xb7/0x180 mm/slub.c:1494 slab_free mm/slub.c:3080 [inline] kmem_cache_free+0x10c/0x2c0 mm/slub.c:3096 shmem_free_in_core_inode+0x90/0xb0 mm/shmem.c:3729 i_callback+0x4c/0x70 fs/inode.c:220 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch+0x446/0x980 kernel/rcu/tree.c:2167 rcu_core+0x4bd/0xbd0 kernel/rcu/tree.c:2387 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2396 __do_softirq+0x236/0x660 kernel/softirq.c:292 The buggy address belongs to the object at ffff8881d4eb7090 which belongs to the cache shmem_inode_cache of size 760 The buggy address is located 312 bytes inside of 760-byte region [ffff8881d4eb7090, ffff8881d4eb7388) The buggy address belongs to the page: page:ffffea000753ad00 refcount:1 mapcount:0 mapping:ffff8881f5d02000 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d02000 raw: 0000000000000000 0000000000120012 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+0x35e/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x1296/0x1310 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x202/0x4b0 mm/page_alloc.c:4894 alloc_slab_page+0x3c/0x3b0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x93/0x420 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x29e/0x420 mm/slub.c:2667 __slab_alloc+0x63/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0x12c/0x270 mm/slub.c:2842 shmem_alloc_inode+0x1a/0x30 mm/shmem.c:3719 alloc_inode fs/inode.c:231 [inline] new_inode_pseudo+0x62/0x210 fs/inode.c:966 new_inode+0x28/0x1e0 fs/inode.c:995 shmem_get_inode+0x107/0x630 mm/shmem.c:2252 shmem_symlink+0x9e/0x4d0 mm/shmem.c:3068 vfs_symlink+0x337/0x4c0 fs/namei.c:4276 do_symlinkat+0x103/0x3b0 fs/namei.c:4303 __do_sys_symlinkat fs/namei.c:4317 [inline] __se_sys_symlinkat fs/namei.c:4314 [inline] __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314 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+0x7e4/0x910 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4956 [inline] __free_pages+0x8c/0x110 mm/page_alloc.c:4962 kfree+0x1ca/0x260 mm/slub.c:4068 kvfree+0x4c/0x50 mm/util.c:625 netdev_freemem+0x3f/0x60 net/core/dev.c:9583 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1743 device_release+0x70/0x1a0 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+0x1fe/0x2c0 lib/kobject.c:764 netdev_run_todo+0xae4/0xc70 net/core/dev.c:9488 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112 tun_detach drivers/net/tun.c:766 [inline] tun_chr_close+0xc4/0x140 drivers/net/tun.c:3563 __fput+0x2a3/0x730 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x146/0x170 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x195/0x1b0 arch/x86/entry/common.c:163 prepare_exit_to_usermode+0x18e/0x1f0 arch/x86/entry/common.c:194 Memory state around the buggy address: ffff8881d4eb7080: fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881d4eb7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881d4eb7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881d4eb7200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881d4eb7280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== 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: 0 PID: 329 Comm: syz-executor Tainted: G B 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f6e09cf0 EFLAGS: 00010006 RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881f31dcec0 RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881d4eb71c0 RBP: ffff8881f6e09d30 R08: 0000000000000004 R09: 0000000000000003 R10: ffffed103edc1398 R11: 1ffff1103edc1398 R12: 00000000ffffa058 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881d4eb71c0 FS: 000055556a005500(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001dea33000 CR4: 00000000003406b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448 expire_timers kernel/time/timer.c:1488 [inline] __run_timers+0x84b/0xb60 kernel/time/timer.c:1817 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830 __do_softirq+0x236/0x660 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x197/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:539 [inline] smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834 RIP: 0010:__hrtimer_init+0x13c/0x280 kernel/time/hrtimer.c:1441 Code: f7 00 00 74 25 e8 f4 a2 0e 00 49 bd 00 00 00 00 00 fc ff df 48 c7 c7 40 c8 88 84 44 89 fe e8 3b 2c d6 02 0f 0b 45 31 ff eb 17 <46> 8b 3c a5 a0 c7 88 84 e8 c7 a2 0e 00 49 bd 00 00 00 00 00 fc ff RSP: 0018:ffff8881f0dd7c38 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff8150dbde RBX: ffff8881f0dd7d20 RCX: 0000000000000000 RDX: ffff8881f31dcec0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff8881f0dd7c68 R08: dffffc0000000000 R09: ffff8881f0dd7d20 R10: ffffed103e1bafad R11: 1ffff1103e1bafa4 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001 __hrtimer_init_sleeper kernel/time/hrtimer.c:1894 [inline] hrtimer_init_sleeper+0x41/0x1f0 kernel/time/hrtimer.c:1909 hrtimer_init_sleeper_on_stack include/linux/hrtimer.h:398 [inline] hrtimer_nanosleep+0x14e/0x440 kernel/time/hrtimer.c:1993 common_nsleep+0x2c/0x40 kernel/time/posix-timers.c:1203 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1231 [inline] __se_sys_clock_nanosleep+0x305/0x3a0 kernel/time/posix-timers.c:1208 __x64_sys_clock_nanosleep+0x9b/0xb0 kernel/time/posix-timers.c:1208 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7fc8bebb31e3 Code: 1f 84 00 00 00 00 00 83 ff 03 74 7b 83 ff 02 b8 fa ff ff ff 49 89 ca 0f 44 f8 80 3d 5e 33 1c 00 00 74 14 b8 e6 00 00 00 0f 05 d8 c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec 28 48 89 54 24 10 RSP: 002b:00007ffd9020e2c8 EFLAGS: 00000202 ORIG_RAX: 00000000000000e6 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc8bebb31e3 RDX: 00007ffd9020e2e0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007ffd903bc080 R09: 00007ffd903bc0b0 R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd9020e730 R13: 0000000000000004 R14: 00007ffd9020e31c R15: 00007ffd9020e3b0 Modules linked in: CR2: 0000000000000000 ---[ end trace eea4dd7222bc23fd ]--- RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f6e09cf0 EFLAGS: 00010006 RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881f31dcec0 RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881d4eb71c0 RBP: ffff8881f6e09d30 R08: 0000000000000004 R09: 0000000000000003 R10: ffffed103edc1398 R11: 1ffff1103edc1398 R12: 00000000ffffa058 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881d4eb71c0 FS: 000055556a005500(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001dea33000 CR4: 00000000003406b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 00 00 add %al,(%rax) 2: 74 25 je 0x29 4: e8 f4 a2 0e 00 call 0xea2fd 9: 49 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%r13 10: fc ff df 13: 48 c7 c7 40 c8 88 84 mov $0xffffffff8488c840,%rdi 1a: 44 89 fe mov %r15d,%esi 1d: e8 3b 2c d6 02 call 0x2d62c5d 22: 0f 0b ud2 24: 45 31 ff xor %r15d,%r15d 27: eb 17 jmp 0x40 * 29: 46 8b 3c a5 a0 c7 88 mov -0x7b773860(,%r12,4),%r15d <-- trapping instruction 30: 84 31: e8 c7 a2 0e 00 call 0xea2fd 36: 49 rex.WB 37: bd 00 00 00 00 mov $0x0,%ebp 3c: 00 fc add %bh,%ah 3e: ff .byte 0xff