Subject: Re: [syzbot] [net?] possible deadlock in unix_del_edges

From: syzbot <[email-masked]>
Date: Sat, 06 Apr 2024 08:15:03 -0700

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

006703][    T1] usbcore: registered new interface driver dln2
[    8.008304][    T1] usbcore: registered new interface driver pn533_usb
[    8.015792][    T1] nfcsim 0.2 initialized
[    8.016960][    T1] usbcore: registered new interface driver port100
[    8.018599][    T1] usbcore: registered new interface driver nfcmrvl
[    8.024908][    T1] Loading iSCSI transport class v2.0-870.
[    8.043578][    T1] virtio_scsi virtio0: 1/0/0 default/read/poll queues
[    8.053585][    T1] ------------[ cut here ]------------
[    8.054621][    T1] refcount_t: decrement hit 0; leaking memory.
[    8.056227][    T1] WARNING: CPU: 0 PID: 1 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0
[    8.057690][    T1] Modules linked in:
[    8.058278][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.9.0-rc1-syzkaller-00291-g4090fa373f0e-dirty #0
[    8.059690][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
[    8.061033][    T1] RIP: 0010:refcount_warn_saturate+0xfa/0x1d0
[    8.061863][    T1] Code: b2 00 00 00 e8 97 bb e9 fc 5b 5d c3 cc cc cc cc e8 8b bb e9 fc c6 05 2e c7 e7 0a 01 90 48 c7 c7 e0 33 1f 8c e8 c7 57 ac fc 90 <0f> 0b 90 90 eb d9 e8 6b bb e9 fc c6 05 0b c7 e7 0a 01 90 48 c7 c7
[    8.066117][    T1] RSP: 0000:ffffc90000066e18 EFLAGS: 00010246
[    8.067097][    T1] RAX: 9bcc421b8c8b6e00 RBX: ffff8881407a5a9c RCX: ffff8880166d0000
[    8.068202][    T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[    8.069406][    T1] RBP: 0000000000000004 R08: ffffffff815800a2 R09: fffffbfff1c396e0
[    8.070770][    T1] R10: dffffc0000000000 R11: fffffbfff1c396e0 R12: ffffea000502cdc0
[    8.071923][    T1] R13: ffffea000502cdc8 R14: 1ffffd4000a059b9 R15: 0000000000000000
[    8.073195][    T1] FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
[    8.074997][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    8.076208][    T1] CR2: ffff88823ffff000 CR3: 000000000e132000 CR4: 00000000003506f0
[    8.077586][    T1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    8.079021][    T1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    8.080171][    T1] Call Trace:
[    8.080710][    T1]  <TASK>
[    8.081192][    T1]  ? __warn+0x163/0x4e0
[    8.082027][    T1]  ? refcount_warn_saturate+0xfa/0x1d0
[    8.083285][    T1]  ? report_bug+0x2b3/0x500
[    8.084102][    T1]  ? refcount_warn_saturate+0xfa/0x1d0
[    8.084911][    T1]  ? handle_bug+0x3e/0x70
[    8.085560][    T1]  ? exc_invalid_op+0x1a/0x50
[    8.086541][    T1]  ? asm_exc_invalid_op+0x1a/0x20
[    8.087289][    T1]  ? __warn_printk+0x292/0x360
[    8.088095][    T1]  ? refcount_warn_saturate+0xfa/0x1d0
[    8.089127][    T1]  ? refcount_warn_saturate+0xf9/0x1d0
[    8.090489][    T1]  __free_pages_ok+0xc60/0xd90
[    8.091183][    T1]  make_alloc_exact+0xa3/0xf0
[    8.092072][    T1]  vring_alloc_queue_split+0x20a/0x600
[    8.093385][    T1]  ? __pfx_vring_alloc_queue_split+0x10/0x10
[    8.094888][    T1]  ? vp_find_vqs+0x4c/0x4e0
[    8.095629][    T1]  ? virtscsi_probe+0x3ea/0xf60
[    8.096312][    T1]  ? virtio_dev_probe+0x991/0xaf0
[    8.097239][    T1]  ? really_probe+0x2b8/0xad0
[    8.098468][    T1]  ? driver_probe_device+0x50/0x430
[    8.099254][    T1]  vring_create_virtqueue_split+0xc6/0x310
[    8.100277][    T1]  ? ret_from_fork+0x4b/0x80
[    8.100955][    T1]  ? __pfx_vring_create_virtqueue_split+0x10/0x10
[    8.101863][    T1]  vring_create_virtqueue+0xca/0x110
[    8.102735][    T1]  ? __pfx_vp_notify+0x10/0x10
[    8.103769][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.104746][    T1]  setup_vq+0xe9/0x2d0
[    8.105350][    T1]  ? __pfx_vp_notify+0x10/0x10
[    8.106064][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.106837][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.107892][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.108758][    T1]  vp_setup_vq+0xbf/0x330
[    8.109837][    T1]  ? __pfx_vp_config_changed+0x10/0x10
[    8.110831][    T1]  ? ioread16+0x2f/0x90
[    8.111461][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.112303][    T1]  vp_find_vqs_msix+0x8b2/0xc80
[    8.113109][    T1]  vp_find_vqs+0x4c/0x4e0
[    8.113869][    T1]  virtscsi_init+0x8db/0xd00
[    8.114601][    T1]  ? __pfx_virtscsi_init+0x10/0x10
[    8.115406][    T1]  ? __pfx_default_calc_sets+0x10/0x10
[    8.116284][    T1]  ? scsi_host_alloc+0xa57/0xea0
[    8.117252][    T1]  ? vp_get+0xfd/0x140
[    8.118053][    T1]  virtscsi_probe+0x3ea/0xf60
[    8.118880][    T1]  ? __pfx_virtscsi_probe+0x10/0x10
[    8.119741][    T1]  ? kernfs_add_one+0x156/0x8b0
[    8.120734][    T1]  ? virtio_no_restricted_mem_acc+0x9/0x10
[    8.121670][    T1]  ? virtio_features_ok+0x10c/0x270
[    8.122793][    T1]  virtio_dev_probe+0x991/0xaf0
[    8.123599][    T1]  ? __pfx_virtio_dev_probe+0x10/0x10
[    8.124434][    T1]  really_probe+0x2b8/0xad0
[    8.125161][    T1]  __driver_probe_device+0x1a2/0x390
[    8.125961][    T1]  driver_probe_device+0x50/0x430
[    8.126905][    T1]  __driver_attach+0x45f/0x710
[    8.127791][    T1]  ? __pfx___driver_attach+0x10/0x10
[    8.128630][    T1]  bus_for_each_dev+0x239/0x2b0
[    8.129617][    T1]  ? __pfx___driver_attach+0x10/0x10
[    8.130766][    T1]  ? __pfx_bus_for_each_dev+0x10/0x10
[    8.131869][    T1]  ? do_raw_spin_unlock+0x13c/0x8b0
[    8.133108][    T1]  bus_add_driver+0x347/0x620
[    8.134579][    T1]  driver_register+0x23a/0x320
[    8.135468][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.136268][    T1]  virtio_scsi_init+0x65/0xe0
[    8.137251][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.138124][    T1]  do_one_initcall+0x248/0x880
[    8.139180][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.140100][    T1]  ? __pfx_lockdep_hardirqs_on_prepare+0x10/0x10
[    8.141028][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    8.141940][    T1]  ? __pfx_parse_args+0x10/0x10
[    8.142812][    T1]  ? do_initcalls+0x1c/0x80
[    8.143461][    T1]  ? rcu_is_watching+0x15/0xb0
[    8.144181][    T1]  do_initcall_level+0x157/0x210
[    8.144944][    T1]  do_initcalls+0x3f/0x80
[    8.145717][    T1]  kernel_init_freeable+0x435/0x5d0
[    8.146491][    T1]  ? __pfx_kernel_init_freeable+0x10/0x10
[    8.147543][    T1]  ? __pfx_lockdep_hardirqs_on_prepare+0x10/0x10
[    8.148835][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.149734][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.150860][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.151964][    T1]  kernel_init+0x1d/0x2b0
[    8.152905][    T1]  ret_from_fork+0x4b/0x80
[    8.154244][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.155345][    T1]  ret_from_fork_asm+0x1a/0x30
[    8.156184][    T1]  </TASK>
[    8.156670][    T1] Kernel panic - not syncing: kernel: panic_on_warn set ...
[    8.157851][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.9.0-rc1-syzkaller-00291-g4090fa373f0e-dirty #0
[    8.161190][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
[    8.162871][    T1] Call Trace:
[    8.162871][    T1]  <TASK>
[    8.162871][    T1]  dump_stack_lvl+0x241/0x360
[    8.162871][    T1]  ? __pfx_dump_stack_lvl+0x10/0x10
[    8.162871][    T1]  ? __pfx__printk+0x10/0x10
[    8.162871][    T1]  ? _printk+0xd5/0x120
[    8.162871][    T1]  ? vscnprintf+0x5d/0x90
[    8.162871][    T1]  panic+0x349/0x860
[    8.162871][    T1]  ? __warn+0x172/0x4e0
[    8.162871][    T1]  ? __pfx_panic+0x10/0x10
[    8.162871][    T1]  ? show_trace_log_lvl+0x4e6/0x520
[    8.162871][    T1]  ? ret_from_fork_asm+0x1a/0x30
[    8.162871][    T1]  __warn+0x346/0x4e0
[    8.162871][    T1]  ? refcount_warn_saturate+0xfa/0x1d0
[    8.162871][    T1]  report_bug+0x2b3/0x500
[    8.162871][    T1]  ? refcount_warn_saturate+0xfa/0x1d0
[    8.162871][    T1]  handle_bug+0x3e/0x70
[    8.162871][    T1]  exc_invalid_op+0x1a/0x50
[    8.162871][    T1]  asm_exc_invalid_op+0x1a/0x20
[    8.162871][    T1] RIP: 0010:refcount_warn_saturate+0xfa/0x1d0
[    8.162871][    T1] Code: b2 00 00 00 e8 97 bb e9 fc 5b 5d c3 cc cc cc cc e8 8b bb e9 fc c6 05 2e c7 e7 0a 01 90 48 c7 c7 e0 33 1f 8c e8 c7 57 ac fc 90 <0f> 0b 90 90 eb d9 e8 6b bb e9 fc c6 05 0b c7 e7 0a 01 90 48 c7 c7
[    8.162871][    T1] RSP: 0000:ffffc90000066e18 EFLAGS: 00010246
[    8.162871][    T1] RAX: 9bcc421b8c8b6e00 RBX: ffff8881407a5a9c RCX: ffff8880166d0000
[    8.162871][    T1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[    8.162871][    T1] RBP: 0000000000000004 R08: ffffffff815800a2 R09: fffffbfff1c396e0
[    8.162871][    T1] R10: dffffc0000000000 R11: fffffbfff1c396e0 R12: ffffea000502cdc0
[    8.162871][    T1] R13: ffffea000502cdc8 R14: 1ffffd4000a059b9 R15: 0000000000000000
[    8.162871][    T1]  ? __warn_printk+0x292/0x360
[    8.162871][    T1]  ? refcount_warn_saturate+0xf9/0x1d0
[    8.162871][    T1]  __free_pages_ok+0xc60/0xd90
[    8.162871][    T1]  make_alloc_exact+0xa3/0xf0
[    8.162871][    T1]  vring_alloc_queue_split+0x20a/0x600
[    8.162871][    T1]  ? __pfx_vring_alloc_queue_split+0x10/0x10
[    8.162871][    T1]  ? vp_find_vqs+0x4c/0x4e0
[    8.162871][    T1]  ? virtscsi_probe+0x3ea/0xf60
[    8.162871][    T1]  ? virtio_dev_probe+0x991/0xaf0
[    8.162871][    T1]  ? really_probe+0x2b8/0xad0
[    8.162871][    T1]  ? driver_probe_device+0x50/0x430
[    8.162871][    T1]  vring_create_virtqueue_split+0xc6/0x310
[    8.162871][    T1]  ? ret_from_fork+0x4b/0x80
[    8.162871][    T1]  ? __pfx_vring_create_virtqueue_split+0x10/0x10
[    8.162871][    T1]  vring_create_virtqueue+0xca/0x110
[    8.162871][    T1]  ? __pfx_vp_notify+0x10/0x10
[    8.162871][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.162871][    T1]  setup_vq+0xe9/0x2d0
[    8.162871][    T1]  ? __pfx_vp_notify+0x10/0x10
[    8.162871][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.212873][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.212873][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.212873][    T1]  vp_setup_vq+0xbf/0x330
[    8.212873][    T1]  ? __pfx_vp_config_changed+0x10/0x10
[    8.212873][    T1]  ? ioread16+0x2f/0x90
[    8.212873][    T1]  ? __pfx_virtscsi_ctrl_done+0x10/0x10
[    8.212873][    T1]  vp_find_vqs_msix+0x8b2/0xc80
[    8.212873][    T1]  vp_find_vqs+0x4c/0x4e0
[    8.212873][    T1]  virtscsi_init+0x8db/0xd00
[    8.212873][    T1]  ? __pfx_virtscsi_init+0x10/0x10
[    8.212873][    T1]  ? __pfx_default_calc_sets+0x10/0x10
[    8.212873][    T1]  ? scsi_host_alloc+0xa57/0xea0
[    8.212873][    T1]  ? vp_get+0xfd/0x140
[    8.212873][    T1]  virtscsi_probe+0x3ea/0xf60
[    8.212873][    T1]  ? __pfx_virtscsi_probe+0x10/0x10
[    8.212873][    T1]  ? kernfs_add_one+0x156/0x8b0
[    8.212873][    T1]  ? virtio_no_restricted_mem_acc+0x9/0x10
[    8.212873][    T1]  ? virtio_features_ok+0x10c/0x270
[    8.212873][    T1]  virtio_dev_probe+0x991/0xaf0
[    8.212873][    T1]  ? __pfx_virtio_dev_probe+0x10/0x10
[    8.212873][    T1]  really_probe+0x2b8/0xad0
[    8.212873][    T1]  __driver_probe_device+0x1a2/0x390
[    8.212873][    T1]  driver_probe_device+0x50/0x430
[    8.212873][    T1]  __driver_attach+0x45f/0x710
[    8.212873][    T1]  ? __pfx___driver_attach+0x10/0x10
[    8.212873][    T1]  bus_for_each_dev+0x239/0x2b0
[    8.212873][    T1]  ? __pfx___driver_attach+0x10/0x10
[    8.212873][    T1]  ? __pfx_bus_for_each_dev+0x10/0x10
[    8.212873][    T1]  ? do_raw_spin_unlock+0x13c/0x8b0
[    8.212873][    T1]  bus_add_driver+0x347/0x620
[    8.212873][    T1]  driver_register+0x23a/0x320
[    8.212873][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.212873][    T1]  virtio_scsi_init+0x65/0xe0
[    8.212873][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.212873][    T1]  do_one_initcall+0x248/0x880
[    8.212873][    T1]  ? __pfx_virtio_scsi_init+0x10/0x10
[    8.212873][    T1]  ? __pfx_lockdep_hardirqs_on_prepare+0x10/0x10
[    8.212873][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    8.212873][    T1]  ? __pfx_parse_args+0x10/0x10
[    8.212873][    T1]  ? do_initcalls+0x1c/0x80
[    8.212873][    T1]  ? rcu_is_watching+0x15/0xb0
[    8.212873][    T1]  do_initcall_level+0x157/0x210
[    8.212873][    T1]  do_initcalls+0x3f/0x80
[    8.212873][    T1]  kernel_init_freeable+0x435/0x5d0
[    8.212873][    T1]  ? __pfx_kernel_init_freeable+0x10/0x10
[    8.212873][    T1]  ? __pfx_lockdep_hardirqs_on_prepare+0x10/0x10
[    8.212873][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.212873][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.212873][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.212873][    T1]  kernel_init+0x1d/0x2b0
[    8.212873][    T1]  ret_from_fork+0x4b/0x80
[    8.212873][    T1]  ? __pfx_kernel_init+0x10/0x10
[    8.212873][    T1]  ret_from_fork_asm+0x1a/0x30
[    8.212873][    T1]  </TASK>
[    8.212873][    T1] Kernel Offset: disabled
[    8.212873][    T1] Rebooting in 86400 seconds..

syzkaller build log:
go env (err=<nil>)
GO111MODULE='auto'
GOARCH='amd64'
GOBIN=''
GOCACHE='/syzkaller/.cache/go-build'
GOENV='/syzkaller/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/syzkaller/jobs-2/linux/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/syzkaller/jobs-2/linux/gopath'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.4'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/syzkaller/jobs-2/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build264214063=/tmp/go-build -gno-record-gcc-switches'

git status (err=<nil>)
HEAD detached at 0ee3535ea
nothing to commit, working tree clean

tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
go list -f '{{.Stale}}' ./sys/syz-sysgen | grep -q false || go install ./sys/syz-sysgen
make .descriptions
tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=0ee3535ea8ff21d50e44372bb1cfd147e299ab5b -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240404-085507'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-fuzzer github.com/google/syzkaller/syz-fuzzer
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=0ee3535ea8ff21d50e44372bb1cfd147e299ab5b -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240404-085507'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=0ee3535ea8ff21d50e44372bb1cfd147e299ab5b -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240404-085507'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-stress github.com/google/syzkaller/tools/syz-stress
mkdir -p ./bin/linux_amd64
gcc -o ./bin/linux_amd64/syz-executor executor/executor.cc \
	-m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -Wno-unused-but-set-variable -Wno-unused-command-line-argument -static-pie -fpermissive -w -DGOOS_linux=1 -DGOARCH_amd64=1 \
	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"0ee3535ea8ff21d50e44372bb1cfd147e299ab5b\"

Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=169731ad180000

Tested on:

commit:         4090fa37 af_unix: Replace garbage collection algorithm.
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=be1e18a11ee69044
dashboard link: https://syzkaller.appspot.com/bug?extid=7f7f201cc2668a8fd169
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15b3cca9180000