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panic: kernfs.Dentry.DecRef() called without holding a reference

Status: fixed on 2021/10/27 00:49
Fix commit: 763d7e6e396d Obtain ref on root dentry in mqfs.GetFilesystem.
First crash: 1130d, last: 1126d
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
gvisor panic: kernfs.Dentry.DecRef() called without holding a reference (2) C 61 726d 727d 14/26 fixed on 2022/12/01 12:27

Sample crash report:
panic: kernfs.Dentry.DecRef() called without holding a reference

goroutine 336 [running]:
panic(0x10cb560, 0x14321a8)
	GOROOT/src/runtime/panic.go:1065 +0x565 fp=0xc0006a3738 sp=0xc0006a3670 pc=0x437c65
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).DecRef(0xc0003c9cb0, 0x1476ce0, 0xc0006caa80)
	pkg/sentry/fsimpl/kernfs/kernfs.go:283 +0xb2 fp=0xc0006a3760 sp=0xc0006a3738 pc=0x852d52
gvisor.dev/gvisor/pkg/sentry/vfs.(*Dentry).DecRef(0xc0003c9cb0, 0x1476ce0, 0xc0006caa80)
	pkg/sentry/vfs/dentry.go:157 +0x48 fp=0xc0006a3788 sp=0xc0006a3760 pc=0x7424c8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountDisconnected(0xc00028b078, 0x1476ce0, 0xc0006caa80, 0xc0005b05a0, 0xc00043a700, 0x8, 0xc00043a600, 0x6, 0xc0006a3a08, 0xc00030c8a0, ...)
	pkg/sentry/vfs/mount.go:206 +0x298 fp=0xc0006a3858 sp=0xc0006a3788 pc=0x7514f8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountAt(0xc00028b078, 0x1476ce0, 0xc0006caa80, 0xc0005b05a0, 0xc00043a700, 0x8, 0xc0006a3a38, 0xc00043a600, 0x6, 0xc0006a3a08, ...)
	pkg/sentry/vfs/mount.go:273 +0xd4 fp=0xc0006a38f8 sp=0xc0006a3858 pc=0x7519f4
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Mount(0xc0006caa80, 0x20000480, 0x200004c0, 0x20000500, 0x10, 0x0, 0x7feeafdb0e78, 0x0, 0x0, 0x0, ...)
	pkg/sentry/syscalls/linux/vfs2/mount.go:112 +0x52f fp=0xc0006a3b00 sp=0xc0006a38f8 pc=0xe3a54f
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0006caa80, 0xa5, 0x20000480, 0x200004c0, 0x20000500, 0x10, 0x0, 0x7feeafdb0e78, 0x0, 0x12d7840, ...)
	pkg/sentry/kernel/task_syscall.go:103 +0x13c fp=0xc0006a3c60 sp=0xc0006a3b00 pc=0x9d7cfc
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0006caa80, 0xa5, 0x20000480, 0x200004c0, 0x20000500, 0x10, 0x0, 0x7feeafdb0e78, 0x0, 0x7feeafdb0e78)
	pkg/sentry/kernel/task_syscall.go:238 +0x66 fp=0xc0006a3ce8 sp=0xc0006a3c60 pc=0x9d8e86
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc0006caa80, 0xa5, 0x20000480, 0x200004c0, 0x20000500, 0x10, 0x0, 0x7feeafdb0e78, 0xc0005b0ac8, 0xc0006ace70)
	pkg/sentry/kernel/task_syscall.go:198 +0x98 fp=0xc0006a3d48 sp=0xc0006a3ce8 pc=0x9d8a78
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0006caa80, 0x2, 0xc0006caa80)
	pkg/sentry/kernel/task_syscall.go:173 +0x15c fp=0xc0006a3e18 sp=0xc0006a3d48 pc=0x9d841c
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0x0, 0xc0006caa80, 0x144a900, 0x0)
	pkg/sentry/kernel/task_run.go:282 +0xc8c fp=0xc0006a3f60 sp=0xc0006a3e18 pc=0x9cd0ac
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0006caa80, 0xd)
	pkg/sentry/kernel/task_run.go:97 +0x1af fp=0xc0006a3fd0 sp=0xc0006a3f60 pc=0x9cbd2f
runtime.goexit()
	src/runtime/asm_amd64.s:1371 +0x1 fp=0xc0006a3fd8 sp=0xc0006a3fd0 pc=0x472861
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:327 +0xfe

Crashes (87):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/10/23 21:08 gvisor 14f4113924c8 282f03fb .config console log report syz C ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 23:40 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 20:43 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 19:40 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 17:07 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 16:56 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-ptrace-2 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 14:25 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 13:24 gvisor 12480f1c4b49 d50eb50a .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 09:58 gvisor 7c267106d1d7 c1132b49 .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 08:45 gvisor 7c267106d1d7 c1132b49 .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 06:09 gvisor 7c267106d1d7 c1132b49 .config console log report info ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/26 01:24 gvisor 7c267106d1d7 c1132b49 .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 23:39 gvisor 7c267106d1d7 c1132b49 .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 21:44 gvisor 7c267106d1d7 78e5f70a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 18:03 gvisor 14f4113924c8 78e5f70a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 14:23 gvisor 14f4113924c8 78e5f70a .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 13:29 gvisor 14f4113924c8 78e5f70a .config console log report info ci-gvisor-kvm panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 11:53 gvisor 14f4113924c8 78e5f70a .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/25 09:19 gvisor 14f4113924c8 4f0000ee .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 23:28 gvisor 14f4113924c8 4f0000ee .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 22:21 gvisor 14f4113924c8 4f0000ee .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 20:51 gvisor 14f4113924c8 4f0000ee .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 17:33 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 15:31 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 14:29 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 13:14 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 11:52 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 11:15 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 11:00 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 10:57 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 10:47 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 08:34 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 08:18 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 07:41 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 07:30 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 06:26 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 05:05 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-race panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/24 00:52 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 20:32 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 17:00 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 16:38 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 16:14 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-race panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 15:02 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 14:48 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 14:32 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 13:00 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 11:26 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-race panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 09:29 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 08:25 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 08:12 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 06:50 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3 panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 06:04 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-3-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/23 04:56 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-ptrace-2-cover panic: kernfs.Dentry.DecRef() called without holding a reference
2021/10/22 16:58 gvisor 14f4113924c8 282f03fb .config console log report info ci-gvisor-kvm-cover panic: kernfs.Dentry.DecRef() called without holding a reference
* Struck through repros no longer work on HEAD.