Hi, We found a bug in Linux 6.10 using syzkaller. It is possibly a page fault bug. The bug report is as follows, but unfortunately there is no generated syzkaller reproducer. Bug report: BUG: unable to handle page fault for address: ffffed10ee2f3093 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 13ffee067 P4D 13ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 11166 Comm: syz.1.137 Not tainted 6.10.0 #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:rht_ptr_rcu include/linux/rhashtable.h:376 [inline] RIP: 0010:__rhashtable_lookup include/linux/rhashtable.h:607 [inline] RIP: 0010:rhashtable_lookup+0x2f7/0x850 include/linux/rhashtable.h:646 Code: 48 8d 9c c1 80 00 00 00 48 89 d8 48 83 c8 01 48 89 44 24 28 49 bd 00 00 00 00 00 fc ff df 48 89 5c 24 50 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 0a b8 28 f8 4c 8b 23 e8 92 ec 2b RSP: 0018:ffffc90000006fa0 EFLAGS: 00010a06 RAX: 1ffff110ee2f3093 RBX: ffff888771798498 RCX: ffff88802cd45000 RDX: 0000000000000302 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000007108 R08: ffffffff89cba429 R09: ffffffff84569d43 R10: 0000000000000003 R11: ffff8880453d9e00 R12: ffff88802cd45004 R13: dffffc0000000000 R14: ffffc90000007090 R15: 00000000e894a683 FS: 0000000000000000(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffed10ee2f3093 CR3: 000000004b92c000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> br_mdb_ip_get_rcu net/bridge/br_multicast.c:102 [inline] br_mdb_entry_skb_get+0x66f/0x990 net/bridge/br_multicast.c:198 br_dev_xmit+0xd82/0x1ad0 net/bridge/br_device.c:101 __netdev_start_xmit include/linux/netdevice.h:4882 [inline] netdev_start_xmit include/linux/netdevice.h:4896 [inline] xmit_one net/core/dev.c:3578 [inline] dev_hard_start_xmit+0x1d9/0x410 net/core/dev.c:3594 __dev_queue_xmit+0x1b40/0x3b40 net/core/dev.c:4393 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0xf91/0x15b0 net/ipv6/ip6_output.c:137 ip6_finish_output+0x43b/0x8f0 net/ipv6/ip6_output.c:222 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] ndisc_send_skb+0xb6c/0x11e0 net/ipv6/ndisc.c:509 addrconf_rs_timer+0x3a3/0x650 net/ipv6/addrconf.c:4039 call_timer_fn+0xff/0x240 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers kernel/time/timer.c:2417 [inline] __run_timer_base+0x734/0x9a0 kernel/time/timer.c:2428 run_timer_base kernel/time/timer.c:2437 [inline] run_timer_softirq+0xb3/0x160 kernel/time/timer.c:2447 handle_softirqs+0x272/0x750 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf0/0x1b0 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1043 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_release+0x5ca/0x860 kernel/locking/lockdep.c:5778 Code: 3c 23 00 74 08 4c 89 f7 e8 13 18 85 00 f6 84 24 91 00 00 00 02 75 68 41 f7 c5 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 4b c7 44 3c 08 00 00 00 00 65 48 8b 04 25 RSP: 0018:ffffc9000907f260 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 1ffff9200120fe5e RCX: ffffc9000907f203 RDX: 0000000000000003 RSI: ffffffff8b4c9b40 RDI: ffffffff8ba956e0 RBP: ffffc9000907f398 R08: ffffffff8f245f2f R09: 1ffffffff1e48be5 R10: dffffc0000000000 R11: fffffbfff1e48be6 R12: dffffc0000000000 R13: 0000000000000246 R14: ffffc9000907f2f0 R15: 1ffff9200120fe58 rcu_lock_release include/linux/rcupdate.h:339 [inline] rcu_read_unlock_sched include/linux/rcupdate.h:894 [inline] pfn_valid+0x3db/0x430 include/linux/mmzone.h:2032 page_table_check_clear+0x1e/0x540 mm/page_table_check.c:70 get_and_clear_full_ptes include/linux/pgtable.h:678 [inline] zap_present_folio_ptes mm/memory.c:1481 [inline] zap_present_ptes+0x664/0x1970 mm/memory.c:1564 zap_pte_range+0x2f3/0x1840 mm/memory.c:1606 zap_pmd_range+0x40f/0x5e0 mm/memory.c:1724 zap_pud_range mm/memory.c:1753 [inline] zap_p4d_range mm/memory.c:1774 [inline] unmap_page_range+0x3c9/0x9f0 mm/memory.c:1795 unmap_vmas+0x3c4/0x5e0 mm/memory.c:1885 exit_mmap+0x245/0xa20 mm/mmap.c:3341 __mmput+0x114/0x3b0 kernel/fork.c:1346 exit_mm+0x207/0x2e0 kernel/exit.c:567 do_exit+0x996/0x2560 kernel/exit.c:863 do_group_exit+0x1fd/0x2b0 kernel/exit.c:1025 __do_sys_exit_group kernel/exit.c:1036 [inline] __se_sys_exit_group kernel/exit.c:1034 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1034 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x7e/0x150 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x67/0x6f RIP: 0033:0x7f87bf3809b9 Code: Unable to access opcode bytes at 0x7f87bf38098f. RSP: 002b:00007ffc9a3fa668 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f87bf3809b9 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffc9a3fa6bc R08: 00007ffc9a3fa74f R09: 0000000000037b19 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000032 R13: 0000000000037b19 R14: 00000000000378e1 R15: 00007ffc9a3fa710 </TASK> Modules linked in: CR2: ffffed10ee2f3093 ---[ end trace 0000000000000000 ]--- RIP: 0010:rht_ptr_rcu include/linux/rhashtable.h:376 [inline] RIP: 0010:__rhashtable_lookup include/linux/rhashtable.h:607 [inline] RIP: 0010:rhashtable_lookup+0x2f7/0x850 include/linux/rhashtable.h:646 Code: 48 8d 9c c1 80 00 00 00 48 89 d8 48 83 c8 01 48 89 44 24 28 49 bd 00 00 00 00 00 fc ff df 48 89 5c 24 50 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 0a b8 28 f8 4c 8b 23 e8 92 ec 2b RSP: 0018:ffffc90000006fa0 EFLAGS: 00010a06 RAX: 1ffff110ee2f3093 RBX: ffff888771798498 RCX: ffff88802cd45000 RDX: 0000000000000302 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000007108 R08: ffffffff89cba429 R09: ffffffff84569d43 R10: 0000000000000003 R11: ffff8880453d9e00 R12: ffff88802cd45004 R13: dffffc0000000000 R14: ffffc90000007090 R15: 00000000e894a683 FS: 0000000000000000(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffed10ee2f3093 CR3: 000000004b92c000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 48 8d 9c c1 80 00 00 lea 0x80(%rcx,%rax,8),%rbx 7: 00 8: 48 89 d8 mov %rbx,%rax b: 48 83 c8 01 or $0x1,%rax f: 48 89 44 24 28 mov %rax,0x28(%rsp) 14: 49 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%r13 1b: fc ff df 1e: 48 89 5c 24 50 mov %rbx,0x50(%rsp) 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 48 89 df mov %rbx,%rdi 34: e8 0a b8 28 f8 call 0xf828b843 39: 4c 8b 23 mov (%rbx),%r12 3c: e8 .byte 0xe8 3d: 92 xchg %eax,%edx 3e: ec in (%dx),%al 3f: 2b .byte 0x2b -- Yours sincerely, Xingyu
