Hello, I see that syzbot found the following crash. syzbot <syzbot+0b10582e8ee2a6253de7@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > BUG: Bad page map in process syz-executor3 pte:ffffffff8901f947 > pmd:18d73f067 > addr:000000006b20cb06 vm_flags:180400fb anon_vma: (null) > mapping:000000007878cb6c index:b7 > file:kcov fault: (null) mmap:kcov_mmap readpage: (null) > CPU: 0 PID: 19022 Comm: syz-executor3 Not tainted 4.19.0-rc2+ #4 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 > print_bad_pte.cold.111+0x1e6/0x24b mm/memory.c:773 > _vm_normal_page+0x248/0x3c0 mm/memory.c:859 > zap_pte_range mm/memory.c:1311 [inline] > zap_pmd_range mm/memory.c:1440 [inline] > zap_pud_range mm/memory.c:1469 [inline] > zap_p4d_range mm/memory.c:1490 [inline] > unmap_page_range+0x9a5/0x2000 mm/memory.c:1511 > unmap_single_vma+0x19b/0x310 mm/memory.c:1556 > unmap_vmas+0x125/0x200 mm/memory.c:1586 > exit_mmap+0x2be/0x590 mm/mmap.c:3093 > __mmput kernel/fork.c:1001 [inline] > mmput+0x247/0x610 kernel/fork.c:1022 > exit_mm kernel/exit.c:545 [inline] > do_exit+0xe6f/0x2610 kernel/exit.c:854 > do_group_exit+0x177/0x440 kernel/exit.c:970 > get_signal+0x8b0/0x1980 kernel/signal.c:2513 > do_signal+0x9c/0x21e0 arch/x86/kernel/signal.c:816 > exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 > prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] > syscall_return_slowpath arch/x86/entry/common.c:268 [inline] > do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x457099 > Code: Bad RIP value. > RSP: 002b:00007f9decd04cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 00000000009300a8 RCX: 0000000000457099 > RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000009300a8 > RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000009300ac > R13: 00007ffe4545d67f R14: 00007f9decd059c0 R15: 0000000000000000 I'm running the 4.18.8 kernel on Fedora (uname -r is 4.18.8-200.fc28.x86_64). Suddenly, my computer freezed completely. After a reboot, I've found the following in the logs: swap_info_get: Bad swap offset entry 1ffffffffffff BUG: Bad page map in process gdbus pte:400000000000000 pmd:a9ed2067 addr:00000000bd2fe465 vm_flags:08000070 anon_vma: (null) map> file:libgvfsdbus.so fault:ext4_filemap_fault mmap:ext4_file_mmap read> CPU: 2 PID: 21057 Comm: gdbus Tainted: G B OE 4.18.8-200.> Hardware name: ASUS All Series/Z97-K, BIOS 2305 10/09/2014 Call Trace: dump_stack+0x5c/0x80 print_bad_pte.cold.102+0x9a/0xc4 ? __swap_info_get.cold.49+0x2f/0x4b unmap_page_range+0x85d/0xba0 unmap_vmas+0x7a/0xb0 exit_mmap+0xaa/0x190 mmput+0x5f/0x130 do_exit+0x280/0xae0 do_group_exit+0x3a/0xa0 get_signal+0x276/0x590 do_signal+0x36/0x610 exit_to_usermode_loop+0x71/0xd0 do_syscall_64+0x14d/0x160 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f02c71f93e9 Code: Bad RIP value. RSP: 002b:00007f02bf7fdce0 EFLAGS: 00000293 ORIG_RAX: 0000000000000007 RAX: fffffffffffffdfc RBX: 00007f02c001f950 RCX: 00007f02c71f93e9 RDX: 00000000ffffffff RSI: 0000000000000001 RDI: 00007f02c001f950 RBP: 0000000000000001 R08: 0000000000000000 R09: 00007f02c001d898 R10: 00007f02c0005280 R11: 0000000000000293 R12: 00000000ffffffff R13: 00007f02c7b85520 R14: 00000000ffffffff R15: 0000000000000002 BUG: Bad rss-counter state mm:000000003b7d4ec4 idx:2 val:-1 The bug reported by syzbot is very recent and the stack trace looks like the one I encountered, so I decided to post here. Unfortunately, I'm running a distribution kernel and my kernel is tainted (WireGuard module). I will try to reproduce it with a vanilla kernel and without any out-of-tree modules, if having a human reproducer would be of any help. Thanks, Yagmur Oymak
