BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 UID: 0 PID: 2675 Comm: syz.0.281 Not tainted 6.11.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 RIP: 0010:_compound_head include/linux/page-flags.h:240 [inline] RIP: 0010:put_page include/linux/mm.h:1550 [inline] RIP: 0010:skb_page_unref include/linux/skbuff_ref.h:44 [inline] RIP: 0010:__skb_frag_unref include/linux/skbuff_ref.h:57 [inline] RIP: 0010:skb_release_data+0xf1/0x200 net/core/skbuff.c:1120 Code: 00 0f 84 ab 00 00 00 4b 8d 5c 25 30 45 31 f6 eb 16 49 ff c6 43 0f b6 44 2c 02 48 83 c3 10 49 39 c6 0f 83 8b 00 00 00 48 8b 2b <48> 8b 45 08 a8 01 75 3d 66 90 66 90 83 7d 34 00 0f 84 d8 00 00 00 RSP: 0018:ffffc900000e09f8 EFLAGS: 00010246 RAX: ffff8881022ad440 RBX: ffff8881022ad570 RCX: 0000000000000100 RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff888103333e00 RBP: 0000000000000000 R08: 0000000000000029 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881022ad440 R13: 0000000000000100 R14: 0000000000000000 R15: ffff888103333e00 FS: 0000000000000000(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 00000000034aa000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> skb_release_all net/core/skbuff.c:1191 [inline] __kfree_skb+0x24/0xa0 net/core/skbuff.c:1205 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3409 [inline] tcp_ack+0x92c/0x14f0 net/ipv4/tcp_input.c:4005 tcp_rcv_state_process+0x2ba/0xd10 net/ipv4/tcp_input.c:6764 tcp_v4_do_rcv+0x1c7/0x300 net/ipv4/tcp_ipv4.c:1937 tcp_v4_rcv+0xdc1/0xf30 net/ipv4/tcp_ipv4.c:2349 ip_protocol_deliver_rcu+0x125/0x2b0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0xa4/0x100 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x6a/0x140 net/ipv4/ip_input.c:254 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0x46/0x120 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5663 [inline] __netif_receive_skb+0xa3/0x160 net/core/dev.c:5777 process_backlog+0x1e9/0x420 net/core/dev.c:6110 __napi_poll+0x27/0x1c0 net/core/dev.c:6774 napi_poll net/core/dev.c:6843 [inline] net_rx_action+0x275/0x460 net/core/dev.c:6965 handle_softirqs+0x10c/0x300 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0x4f/0xc0 kernel/softirq.c:637 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline] sysvec_apic_timer_interrupt+0x92/0xb0 arch/x86/kernel/apic/apic.c:1043 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:deref_stack_reg+0x84/0x90 arch/x86/kernel/unwind_orc.c:408 Code: 39 f9 77 21 48 8b 53 10 4c 39 fa 76 18 49 8d 77 08 31 c0 48 39 ce 76 0d 48 39 d6 77 08 49 8b 07 49 89 06 b0 01 5b 41 5e 41 5f <c3> cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc900038cf738 EFLAGS: 00000287 RAX: 0000000000000001 RBX: ffffc900038cff48 RCX: ffffc900038d0000 RDX: ffffc900038cff50 RSI: ffffc900038cff48 RDI: ffffc900038cf788 RBP: ffffc900038cf7d8 R08: 0000000000000000 R09: ffffffff83ee6324 R10: 0000000000000000 R11: ffffffff81155640 R12: ffffc900038cff50 R13: 0000000000000001 R14: ffffffff83ee6324 R15: ffffc900038cf788 unwind_next_frame+0x9d7/0xc50 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x47/0x70 kernel/stacktrace.c:122 save_stack+0xef/0x140 mm/page_owner.c:156 __reset_page_owner+0x40/0x140 mm/page_owner.c:297 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1094 [inline] free_unref_folios+0x5d3/0xae0 mm/page_alloc.c:2660 folios_put_refs+0x1c1/0x200 mm/swap.c:1039 free_pages_and_swap_cache+0x1c3/0x1f0 mm/swap_state.c:335 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline] tlb_batch_pages_flush mm/mmu_gather.c:149 [inline] tlb_flush_mmu_free mm/mmu_gather.c:366 [inline] tlb_flush_mmu+0x133/0x1a0 mm/mmu_gather.c:373 tlb_finish_mmu+0x41/0x80 mm/mmu_gather.c:465 exit_mmap+0x2cd/0x580 mm/mmap.c:3425 __mmput+0x3d/0x110 kernel/fork.c:1345 exit_mm+0xaa/0x110 kernel/exit.c:571 do_exit+0x1eb/0xac0 kernel/exit.c:869 do_group_exit+0x86/0xa0 kernel/exit.c:1031 get_signal+0x718/0x7d0 kernel/signal.c:2917 arch_do_signal_or_restart+0x89/0x2a0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x57/0x1d0 kernel/entry/common.c:218 do_syscall_64+0x9a/0x170 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6a8b185d19 Code: Unable to access opcode bytes at 0x7f6a8b185cef. RSP: 002b:00007f6a8bf330e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f6a8b375fa8 RCX: 00007f6a8b185d19 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6a8b375fa8 RBP: 00007f6a8b375fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6a8b375fac R13: 0000000000000000 R14: 00007f6a8b49f940 R15: 00007f6a8b49fa28 </TASK> Modules linked in: CR2: 0000000000000008 ---[ end trace 0000000000000000 ]--- RIP: 0010:_compound_head include/linux/page-flags.h:240 [inline] RIP: 0010:put_page include/linux/mm.h:1550 [inline] RIP: 0010:skb_page_unref include/linux/skbuff_ref.h:44 [inline] RIP: 0010:__skb_frag_unref include/linux/skbuff_ref.h:57 [inline] RIP: 0010:skb_release_data+0xf1/0x200 net/core/skbuff.c:1120 Code: 00 0f 84 ab 00 00 00 4b 8d 5c 25 30 45 31 f6 eb 16 49 ff c6 43 0f b6 44 2c 02 48 83 c3 10 49 39 c6 0f 83 8b 00 00 00 48 8b 2b <48> 8b 45 08 a8 01 75 3d 66 90 66 90 83 7d 34 00 0f 84 d8 00 00 00 RSP: 0018:ffffc900000e09f8 EFLAGS: 00010246 RAX: ffff8881022ad440 RBX: ffff8881022ad570 RCX: 0000000000000100 RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff888103333e00 RBP: 0000000000000000 R08: 0000000000000029 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881022ad440 R13: 0000000000000100 R14: 0000000000000000 R15: ffff888103333e00 FS: 0000000000000000(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 00000000034aa000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 00 0f add %cl,(%rdi) 2: 84 ab 00 00 00 4b test %ch,0x4b000000(%rbx) 8: 8d 5c 25 30 lea 0x30(%rbp,%riz,1),%ebx c: 45 31 f6 xor %r14d,%r14d f: eb 16 jmp 0x27 11: 49 ff c6 inc %r14 14: 43 0f b6 44 2c 02 movzbl 0x2(%r12,%r13,1),%eax 1a: 48 83 c3 10 add $0x10,%rbx 1e: 49 39 c6 cmp %rax,%r14 21: 0f 83 8b 00 00 00 jae 0xb2 27: 48 8b 2b mov (%rbx),%rbp * 2a: 48 8b 45 08 mov 0x8(%rbp),%rax <-- trapping instruction 2e: a8 01 test $0x1,%al 30: 75 3d jne 0x6f 32: 66 90 xchg %ax,%ax 34: 66 90 xchg %ax,%ax 36: 83 7d 34 00 cmpl $0x0,0x34(%rbp) 3a: 0f 84 d8 00 00 00 je 0x118