Re: [syzbot] upstream boot error: kernel panic: VFS: Unable to mount root fs on unknown-block(0,0)

[Marco Elver]

On Sat, Jul 03, 2021 at 02:30AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    4b820e16 Revert "ALSA: usb-audio: Reduce latency at playba..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17f16ac4300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=476b9a5c50907dd0
> dashboard link: https://syzkaller.appspot.com/bug?extid=86ab74ebbf8800b62803
> compiler:       Debian clang version 11.0.1-2
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+86ab74ebbf8800b62803@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> e1000: Copyright (c) 1999-2006 Intel Corporation.
> e1000e: Intel(R) PRO/1000 Network Driver
> e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
> sky2: driver version 1.30
> ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
> ehci-pci: EHCI PCI platform driver
> ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
> ohci-pci: OHCI PCI platform driver
> uhci_hcd: USB Universal Host Controller Interface driver
> usbcore: registered new interface driver usblp
> usbcore: registered new interface driver usb-storage
> i8042: PNP: PS/2 Controller [PNP0303:KBD,PNP0f13:MOU] at 0x60,0x64 irq 1,12
> i8042: Warning: Keylock active
> serio: i8042 KBD port at 0x60,0x64 irq 1
> serio: i8042 AUX port at 0x60,0x64 irq 12
> rtc_cmos 00:00: RTC can wake from S4
> rtc_cmos 00:00: registered as rtc0
> rtc_cmos 00:00: alarms up to one day, 114 bytes nvram
> device-mapper: ioctl: 4.45.0-ioctl (2021-03-22) initialised: dm-devel@xxxxxxxxxx
> intel_pstate: CPU model not supported
> hid: raw HID events driver (C) Jiri Kosina
> usbcore: registered new interface driver usbhid
> usbhid: USB HID core driver
> nf_conntrack_irc: failed to register helpers
> nf_conntrack_sip: failed to register helpers
> Initializing XFRM netlink socket
> NET: Registered PF_INET6 protocol family
> Segment Routing with IPv6
> sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
> NET: Registered PF_PACKET protocol family
> 9pnet: Installing 9P2000 support
> Key type dns_resolver registered
> IPI shorthand broadcast: enabled
> sched_clock: Marking stable (2235106141, 17179042)->(2259812022, -7526839)
> registered taskstats version 1
> Loading compiled-in X.509 certificates
> PM:   Magic number: 13:586:166
> printk: console [netcon0] enabled
> netconsole: network logging started
> cfg80211: Loading compiled-in X.509 certificates for regulatory database
> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
> ALSA device list:
>   No soundcards found.
> md: Waiting for all devices to be available before autodetect
> md: If you don't use raid, use raid=noautodetect
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> VFS: Cannot open root device "sda1" or unknown-block(0,0): error -6
> Please append a correct "root=" boot option; here are the available partitions:
> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack_lvl+0xb7/0x103 lib/dump_stack.c:96
>  dump_stack+0x11/0x1a lib/dump_stack.c:103
>  panic+0x1df/0x5ea kernel/panic.c:232
>  mount_block_root+0x259/0x2ae init/do_mounts.c:452
>  mount_root+0x97/0xae init/do_mounts.c:555
>  prepare_namespace+0x27f/0x2ba init/do_mounts.c:607
>  kernel_init_freeable+0x233/0x289 init/main.c:1612
>  kernel_init+0x17/0x2d0 init/main.c:1491
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Kernel Offset: disabled
> Rebooting in 86400 seconds..

I bisected this to "scsi: core: Kill DRIVER_SENSE":

	https://groups.google.com/g/syzkaller-bugs/c/ck9AY2Re2FU

... and per Martin's response should therefore be:

#syz fix: scsi: virtio_scsi: Do not overwrite SCSI status