================================================================== 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 ffff8881f25f31c8 by task kworker/1:10/1153 CPU: 1 PID: 1153 Comm: kworker/1:10 Not tainted 5.4.290-syzkaller-00002-g41adfeb3d639 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: rcu_gp process_srcu 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:539 [inline] smp_apic_timer_interrupt+0x11a/0x490 arch/x86/kernel/apic/apic.c:1161 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834 RIP: 0010:_find_next_bit lib/find_bit.c:48 [inline] RIP: 0010:find_next_bit+0x71/0x100 lib/find_bit.c:70 Code: 03 42 80 3c 28 00 74 08 48 89 df e8 09 9a 67 ff 48 8b 1b 44 89 e1 48 d3 eb 48 d3 e3 49 83 e4 c0 31 ff 48 89 de e8 1f b3 37 ff <48> 85 db 74 34 e8 b5 af 37 ff eb 50 4c 89 e3 48 c1 eb 03 4c 01 fb RSP: 0018:ffff8881e74f7bd8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 RDX: ffff8881e65d0fc0 RSI: 0000000000000003 RDI: 0000000000000000 RBP: ffff8881f6f5d800 R08: ffffffff822c9b41 R09: ffffed103ce9ef81 R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000008 R15: ffffffff864c4d78 srcu_readers_lock_idx kernel/rcu/srcutree.c:255 [inline] srcu_readers_active_idx_check kernel/rcu/srcutree.c:324 [inline] try_check_zero+0x17e/0x360 kernel/rcu/srcutree.c:704 srcu_advance_state kernel/rcu/srcutree.c:1146 [inline] process_srcu+0x1ab/0xc40 kernel/rcu/srcutree.c:1241 process_one_work+0x765/0xd20 kernel/workqueue.c:2290 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436 kthread+0x2da/0x360 kernel/kthread.c:288 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354 Allocated by task 6454: 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] kmem_cache_alloc+0xd9/0x250 mm/slub.c:2842 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3719 alloc_inode fs/inode.c:231 [inline] new_inode_pseudo+0x60/0x210 fs/inode.c:966 new_inode+0x25/0x1d0 fs/inode.c:995 shmem_get_inode+0x10b/0x620 mm/shmem.c:2252 shmem_symlink+0x118/0x5f0 mm/shmem.c:3068 vfs_symlink+0x36c/0x500 fs/namei.c:4276 do_symlinkat+0x19b/0x400 fs/namei.c:4303 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 10: 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] kmem_cache_free+0x10b/0x2c0 mm/slub.c:3096 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch+0x492/0xa00 kernel/rcu/tree.c:2167 rcu_core+0x4c8/0xcb0 kernel/rcu/tree.c:2387 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292 The buggy address belongs to the object at ffff8881f25f3090 which belongs to the cache shmem_inode_cache of size 760 The buggy address is located 312 bytes inside of 760-byte region [ffff8881f25f3090, ffff8881f25f3388) The buggy address belongs to the page: page:ffffea0007c97c00 refcount:1 mapcount:0 mapping:ffff8881f5cff900 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5cff900 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+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] kmem_cache_alloc+0x109/0x250 mm/slub.c:2842 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3719 alloc_inode fs/inode.c:231 [inline] new_inode_pseudo+0x60/0x210 fs/inode.c:966 new_inode+0x25/0x1d0 fs/inode.c:995 shmem_get_inode+0x10b/0x620 mm/shmem.c:2252 shmem_mknod+0x54/0x1a0 mm/shmem.c:2844 lookup_open fs/namei.c:3379 [inline] do_last fs/namei.c:3471 [inline] path_openat+0x184a/0x34b0 fs/namei.c:3683 do_filp_open+0x20b/0x450 fs/namei.c:3713 do_sys_open+0x39c/0x810 fs/open.c:1123 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 bpf_check+0x8aeb/0xb3e0 kernel/bpf/verifier.c:9731 bpf_prog_load kernel/bpf/syscall.c:1724 [inline] __do_sys_bpf kernel/bpf/syscall.c:2891 [inline] __se_sys_bpf+0x8139/0xbcb0 kernel/bpf/syscall.c:2849 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Memory state around the buggy address: ffff8881f25f3080: fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f25f3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881f25f3180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881f25f3200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f25f3280: 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: 1 PID: 17 Comm: ksoftirqd/1 Tainted: G B 5.4.290-syzkaller-00002-g41adfeb3d639 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f5e27b58 EFLAGS: 00010206 RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881f5e11f80 RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881f25f31c0 RBP: ffff8881f5e27d08 R08: ffffffff8154e50e R09: 0000000000000003 R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffffc760 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881f25f31c0 FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001cad1b000 CR4: 00000000003406a0 DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: 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 run_ksoftirqd+0x1f/0x30 kernel/softirq.c:603 smpboot_thread_fn+0x545/0x930 kernel/smpboot.c:165 kthread+0x2da/0x360 kernel/kthread.c:288 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354 Modules linked in: CR2: 0000000000000000 ---[ end trace 7471811b0b9e36ea ]--- RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f5e27b58 EFLAGS: 00010206 RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881f5e11f80 RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881f25f31c0 RBP: ffff8881f5e27d08 R08: ffffffff8154e50e R09: 0000000000000003 R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffffc760 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881f25f31c0 FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001cad1b000 CR4: 00000000003406a0 DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 ---------------- Code disassembly (best guess): 0: 03 42 80 add -0x80(%rdx),%eax 3: 3c 28 cmp $0x28,%al 5: 00 74 08 48 add %dh,0x48(%rax,%rcx,1) 9: 89 df mov %ebx,%edi b: e8 09 9a 67 ff call 0xff679a19 10: 48 8b 1b mov (%rbx),%rbx 13: 44 89 e1 mov %r12d,%ecx 16: 48 d3 eb shr %cl,%rbx 19: 48 d3 e3 shl %cl,%rbx 1c: 49 83 e4 c0 and $0xffffffffffffffc0,%r12 20: 31 ff xor %edi,%edi 22: 48 89 de mov %rbx,%rsi 25: e8 1f b3 37 ff call 0xff37b349 * 2a: 48 85 db test %rbx,%rbx <-- trapping instruction 2d: 74 34 je 0x63 2f: e8 b5 af 37 ff call 0xff37afe9 34: eb 50 jmp 0x86 36: 4c 89 e3 mov %r12,%rbx 39: 48 c1 eb 03 shr $0x3,%rbx 3d: 4c 01 fb add %r15,%rbx